I was with my girlfriend for 4 years and 3 months (to the day). She had always told me that if she was going to end it she'd do it face to face, however, what happened was she acted strange and snapped at me for about 2 weeks then I phoned her and asked what was wrong, asked if she wanted to break up, she said yes. She made me do it to myself... over the phone. When I asked if there was anyone else she said no, when I asked if she could promise me that there was no one else she couldn't do it. She had been talking to an old college tutor of mine, and whether she realised it (she is naïve about people actions during social interaction) she was flirting with him, Facebook, msn, mypace, txting almost everyday. She kept talking about him and she even went shopping while I was in Uni and she met up with him for lunch.
When I pressed her as to why she couldn't promise there wasn't anyone she finally admitted that it was "Nick" (he is no longer a tutor and is 38 years old, we are both 21).
She admitted flirting online with him and he had asked her if she liked him, she had replied yes.
I realise this must look obvious to anyone reading this, but she later said that it was harmless flirting (I'm not sure there is such a thing) and that it meant nothing, she has since promised me that there is no one else.

She has also given reasons such as my anger, violence, jealousy and controlling her. Understandably these are issues I have, I'm not a violent person, I'm an angry one, I get violent when people threaten me or upset me sometimes, I know this fault and have been doing anger management to overcome it (I'm doing well :) )
I also know that I get jealous and can seem to be clingy, but she too knew I had these problems when I went out with her.
I'll tell you a bit about myself so you can get a better image:

I am 5 foot 7 ish (I was often bullied for being small)
I have low self esteem (due to being bullied a lot)
My parents never showed me much affection when I was a kid and I have had a somewhat sheltered life in terms of my parents ethics and views rubbing off on me (you could say I'm old fashioned)

From these facts here's how they have affected me as an adult.

Being short and having low self esteem and the fact that in my parents eyes I am still a child, I feel that when my ex flirts with people right in front of me (as if I'm not there) these men are adults, she is an adult, and I am emasculated, it hurts that she knows my problems but still does this (she says she's not aware she's doing it)
I am clingy but that's because I'm afraid of losing people who I care about, I have lost many relatives and I don't handle the pain of loss very well, having never received much affection until a few years ago, I might not have always been as appreciative of it as I should have.

So, back to her then.
I have made great progress with my anger management and explained the reasons for my jealousy and worry about losing her, but she then said that she "feels different" like "we're not a couple anymore", that "you can love someone and not want to be with them," that she "doesn't know if she loves me" and so on so forth,
To me, that all looks like she's making up excuses, she lied to me, she changed the lock, she won't meet me anymore, she won't even talk on the phone (it looks very suspicious).

She lived with her mum, but her mums moved to malta, meaning she now has to find a roof over her head and a suitable job, this understandably will cause her stress, she's thinking of moving away to find better work etc, but here's the interesting part:
She's known about this for months, she wanted me to get accommodation at uni, she wanted me to buy a car (but I don't need one) she was visibly grumpy about this, then 2 weeks or so into uni and she dumped me
Those 2 weeks she had been off with me, giving me the cold shoulder and not spending time with me (she'd previously voiced concerns about me meeting someone else at uni and going out with them, she also was going to go to uni but she didn't get in)
She said that love doesn't just disappear over night, and that she wouldn't ever sleep with someone she didn't love, the week before she left me we had sex though, meaning either she's lying about who she'll sleep with, or she's so worried about sorting her life out that our relationship doesn't seem important. She dumped me 11 weeks ago and I'm really struggling to understand why, all these facts keep spinning round my head and I can't stop thinking about the worst case scenarios, it's affecting my uni work, my sleep, my eating habits, and to make matters worse I can no longer get her to contact me, which makes it look like the worst case scenario is the more likely.
I know I've made mistakes, but she knew I was a sensitive person, my feelings of inadequacy may well be to blame, but she could have at least reassured me.
Earlier this year we went to japan together, we were so happy, we came back, did various things, went to the zoo, a month before she dumped me was her birthday we had a nice meal out, we were happy, we were happy until I started uni,
I guess what I'm getting at here is does anyone think they understand why she's doing this.
Is she after someone else, is she worried about setting up her first home? Is she worried I'd socially move away from her?
I don't know what I'm expecting from any responses, but I'm at my wits end, I'm exhausted and depressed my work is barely at pass level,
I was going to propose to her, but she left me before I could do it. She's also changed her personality, she now admits that she flirts, and on Facebook "likes justifying completely inappropriate and unacceptable behaviour as banter".
She scrutinises my problems, yet revels in her own, it doesn't make sense as she never used to like guys giving her attention, one old guy used to touch her thigh, knees, or once tired to bend her over the bonnet of his car, (she freaked out and stayed away from him) yet now she thinks of this as mere banter?
Please can someone tell me what's happened to my GF?

Long post, but I got the meat out of it.

I think that you should work on yourself esteem. Some of Hollywood's biggest stars are your height, shorter even. Look it up Stallone, Cruise,.

The most important thing is to not allow yourself to be disrespected. This girl is disrespectful. That's not "love".

Life goes on. How long are you going to waste energy on something that isn't worth the effort?

Most of us go through some bad relationships before we find the one that we want to last forever.

Good luck to you.

Sorry to hear that you are going through this... but your girlfriend, she loved you at some point, she no longer loves you, I am a female I know, I was with this guys were were friend for 5 yrs then we got together, he treated me real nice, but he had an anger problem and the way he he referred to his mom and other females calling them *****es, I knew it was not going to work I knew I wanted out but I sort of stayed in there, then I started avoiding him made excuses every time he wanted to meet up. Dude she does not love you, learn to let go it is going to be hard, she told you that she does not love you accept it, I met someone who really loves me and I the same, it is mutual. I am pretty sure you will find someone who can reciprocate the love you are willing to give. Do not sit and cry over spilt milk, get up and move on with your life. I am so happy now and I am sure if you permit yourself you will be happy too, best of luck, I honestly wish the best for u

I've tried to move on, but I'm struggling, I've tried meditating and I find that having a set of principles to believe in helps me keep my anger in check. But the meditating only stops my pain for a while and when I stop feeling so hurt when I'm awake, I start to have horrible dreams about her.
I know it sounds silly that I'm subjecting myself to this, but I can't let go, it's driving me mad. I can't stop loving her, I've honestly tried, but I can't stand the thought of someone else being with her, she's my first girlfriend, and we're both each others first intimate partners, I thought we were made for each other. How do I get rid of these ideas that simply aren't true and quite frankly destroying me?

Comment on jmjoseph's post
I've got a book on self esteem :),
About disrespect, flirting aside, this is a very recent change, do you think it might be "survival mode" perhaps she feels that the relationship is less important compared to a job and house?

All do respect, forget how she feels, focus on how you feel and don't be distracted by wondering about her, and what she is doing. Meditation is a start, but you must come to know what you are feeling, and how to cope with those feelings. Stay with it until they fades, and you replave them with newer feelings of accomplishment, and discovery, and you have a better handle on dealing with yourself. I also advise some physical exertion, as well as mental exercises to help you bring the focus back to you.

Make a plan of action, that becomes routine, and repeat it every time you think of her. Like polishing your shoes, rearranging the disco collection, read about a new skill, or develop an old one. Anything to give your thought, and actions discipline and control. Meeting new people, and making friends, and talking to family can also help.

Read the stickies for more ideas and insights. Your g/f changed, and you have to adjust.

When you are in a deeply committed relationship with someone, and changes happen that you did not anticipate, and the relationship changes, that means the people in the relationship will do one of two things. They will work through problems because they have a good foundation, and good communication, or, the relationship will splinter and each will go their separate ways.

It is not always possible for people to soften the blow, or feel comfortable in a relationship that is just not working for them. When the truth is finally on the table, and there is no mending or fixing what is wrong, the reasons don't really matter. The only conclusion you can draw is that the relationship is indeed, over.

To keep trying to figure things out will not give you any peace or any greater understanding, nor will it mean that the relationship will resume, or that suddenly everything will be okay again. To keep that light burning by continuously trying to understand what went wrong, will not bring you any closer to her than you are right now. It is still over, no matter how little, or how much you understand.

Some things you just have to let go, and this will come with time. Try to start seeing yourself as a single person who has benefited from a relationship. There are many qualities you had that kept the relationship growing and strong for a long time, and all of that is not lost. Those qualities you will bring to the next relationship too. She is not the only girl in the world.

That she's changed the locks, and refusing to speak to you, and has told you that she doesn't feel that the two of you are a couple anymore, pretty much says the relationship is over.

Should she find that she has made a mistake and wants to try again, I would be very leary of her motives. There is nothing she's going through now that you wouldn't have been there for her, so even considering your theory that stress is motivating her behaviour right now, and she resolves the issues she's facing, does not necessarily mean that she is going to be, or make, a better partner. Try to put your needs first, and be very careful.