I've dated this guy for years... were good together, he's a very loving partner albeit a little possessive. Just 2 days ago he broke up with me (totally my fault).

The reason was that I contacted a male friend; let's name him John when he specifically told me not to. Well we were friends even before my relationship with my guy. Well anyway I contacted John mostly what we did was catch up through text messaging each other. Then after a few days I got really guilty for doing something I knew he didn't want me doing. I told John to please stop texting me because my boyfriend wouldn't like that.

But John kept texting "hey" or "how's life" stuff like that that I changed his name in my contact list to a girl's name just so whenever he sent me those random messages my boyfriend wouldn't get mad. Unfortunately though he found out anyway (he's very keen).

So I ended up admitting what I did, and no surprise there, he dumped me. I was pretty pathetic. I said sorry and I knew I made a mistake I'll do all I can to make it up to you. I broke his trust. He told me I just want to get rid of you; I can't believe you could do this to me.

So the next day I asked advice from girlfriend and I ended up sending him a long text message. He called me right after and we had another fight. The same stuff, like how could I have done that, he can't imagine life with me anymore, it's really over, etc. I was crushed and I told him at least let me try to make it up to you. He told me it was close to impossible to repair what was damaged. And he told me he wanted to see me try hard to fix things between us. He blocked me from his cell, told me "it would be too easy for you, find other means to contact me" then he said goodbye... I'm heartbroken, I feel like the stupidest fool alive. How can I ever make this work?

I hate to break it to you, hun, but you broke his trust. There isn't really any way of getting it back completely. Things would never be the same if you did continue to date.
To be honest, though, it sounds like this guy never really trusted you in the first place, considering he didn't want you talking to your old friend. It was a little bit ridiculous of him to ask you not to contact him. You should be allowed to have whatever friendships you want, as long as you're not cheating, and I assume you weren't. You shouldn't have to put up with that kind of oppression just because your man has some trust issues.
My advice: Move on.

Ignore the jealous fool. You should have told him he can't pick your friends, and now he wants you to jump through some hoops for him?? DON'T!!

I agree that you should not be too down on yourself. Without knowing the detail, his behaviour appears unreasonable. You may feel 'if I hadn't texted this guy we'd still be together' - but unless there is a lot more to this than meets the eye, then a relationship that can end because of a text to a disapproved friend does not appear stable or robust and will probably be tested again on some other fairly low key matter. If in general you feel quite controlled then it is tough to grow in such a relationship or become fulfilled. But context is key when trying to measure how unreasonable his behaviour is. Is he generally controlling? Do you have to manage his behaviour? Was his objection to the guy a serious objection, reasonable?

Even so there are clearly issues between you two that are wrong if such a situation can emerge and be handled this way. On the surface it appears that his unreasonable behaviour has encouraged you to be deceptive: but it is just a superficial observation.