I'm one to write a book so I'm going to try to keep it as simple as I can, but please bear with me anyways~

I broke up with him in October of 2007, our senior year. We had dated for 10 months. We were very attached to one another. We were also very protective over each other. I stopped hanging out with my friends, he stopped hanging out with his friends. We spent every second that we could together, we rearranged our schedules just so that we could have every class together. Everyone told us how unhealthy our relationship was. I eventually began to listen, once I got a job, and all my coworkers were also saying that our relationship was unhealthy. I began to see how he was like my puppet, he allowed me to control him, he followed me around like a puppy, I begun to miss my friends... I realized how I had changed him. He had once been so friendly and goofy with everyone, especially girls. But I felt threatened by this early in the relationship, so I forced him to stop talking, even looking, at other girls. The fact that he allowed me to do this was a turnoff, I tried talking to him about it, but he said he couldn't change back now.. . I'm just now remembering all of this as I write it.
Everyone hated us it seemed. He was like a shell when it came to my friends/our friends... They hated who I had turned him into. They hated how we were always so glued together, how we couldn't keep our hands off each other...
I guess that is what destroyed our relationship.
We had great chemistry together. We understood each other. He loved me for me... but did I love him for him at the time? I don't think so. I always told him he was too romantic, too attached to me, obsessed... We would talk to one another on the phone and I would find myself auto tuning him out, because I found what he was talking about to be boring.
Looking back, I was a horrible girlfriend. I didn't appreciate him for who he was, what he did for me. And in all reality... I didn't allow him to be who he was...
Anyway, after I broke up with him, after a month of him trying to maintain a relationship with me, I cut off communication completely with him. He switched schools for starters. My friend, who despised our relationship, who was a girl, and had been one of his best friends before him and I had started dating, was the one who got through to him. He called my phone one night, she answered, I walked away, and she said something to him. He never called again. I blocked his email, blocked his myspace, and for 2-3 months, had absolutely no contact with him.
In those two months, I relapsed. I had been in rehab my sophomore year for drug and alcohol abuse. I began dating this ugly guy I had never even liked as a friend, moved out of my mom's house, into this guy's mom's house, began paying her rent, began partying nightly and even at work...
I got kicked out of school...
And this was the day I called my ex.
He had begun drinking and partying a lot as well. Which he had never done. I was his first girlfriend, his first everything.
This is such a long story... I'll just skip a lot. I'm back on the right track. I've been sober for 14 months. I'm engaged to someone else.
My ex is "madly insanely head over heels in love" with someone he met at his new school.
He's engaged to her.
I find myself thinking of him constantly though.
Constantly comparing him to my fiancé.
Why do I miss him? Why do I dream about him? Why do I think of him so much?
He seems to be completely moved on.
Why can't I?
I thought I had moved on, but October of last year, after a year of breaking up with him, I remembered all the great aspects of our relationship. All the memories flooded back to me. And since, they have just kept coming.
I had forgotten him.
I have OCD. Could this be a factor?
When I was with him though, I missed my first love, my first love from when I was 12-14.
What's wrong with me?
Could it be that now he is back to being who I had originally fallen in love with... Idk. Please input your opinions.