Should an ex stay and ex?

We've all done it before, broken up with someone because it seemed like the right thing to do at the time only to realize it was a mistake. I've seen all of the articles on how to get over an ex and everything, but what happens when you're the one who did the breaking up? It seems like everyone believes that if you're the one who broke up with your ex, then you are fine. And for anyone who has ever broken up with someone they truly loved, they know it is a lot harder then that.
I'm going to give you a little background on my situation. I was with my ex since the beginning of september of 2008. We had our fights and we weren't perfect, but we were right for each other. We were each other's best friends, and like all best friends, we fought. But somehow we always got over it. We both maintained lives outside of the relationship, careful to not to be overbearing.
I think the first breaking point in our relationship was on my birthday (end of june). I picked him up and took him out to lunch, and we had a good afternoon. Then he had to do a short training for his job, but he promised to come to my birthday dinner with my family later. Needless to say, he didn't show. He made some excuses and made me feel awful, and I refused to see him for a week. We then hung out about 2 times a week for two weeks until I left on a school-related trip (took some classes at another university for 3 weeks). Well, while there, I met another guy. My boyfriend and I got into a huge fight because I was gone. He was jealous of everything I was doing, checking my facebook way too often. I told him to relax and have fun while I was gone, but he just got more mad. I thought that my every-other-day 30 minute phone calls were enough for us, but he wanted every day texting as well, which is unrealistic when you're on a college campus and with others all the time. Well, that other guy and I got increasingly close. I started to like another guy, something I hadn't thought was possible when with my guy.
No, I did not cheat on my guy in those 3 weeks. I knew that was wrong, but when I got back, something just wasn't the same. I felt awful that I had those feelings for another guy and that my boyfriend couldn't know about them. And he got mad at me that I wasn't that happy to see him when I got back. We had never had problems like that before, we had always been ok. Towards the end of August, I hit my breaking point and told him that if we weren't making each other happy anymore, we shouldn't be together anymore. He comforted me and convinced me that he would make it better, we just had to give it time. Over the course of the next month, we stayed together and things were fine. But they weren't great the way they were before. 
I could tell it bothered him that I would be moving the next year, and we both knew how hard it would be on our relationship. He was no longer as supportive of me as he used to be and we had some more problems. At the end of september, I broke up with him.
He was a wreck for the first few weeks following our break up, and in all honesty, I think he still is. I was a wreck too. I spent more hours crying then I would like to admit. I found a few other guys to keep me occupied for that time, but nothing was the same. When I kissed a guy for the first time since my ex, all I could think was how weird it felt. It wasn't right. And I still feel that way.
I miss my boyfriend, and I do still love him. I just don't know what to do about it. I texted him last week to see if he wanted to get lunch this weekend, but then I got sick on friday so we couldn't on saturday, and when asked him about sunday, he said that he had a lot of stuff to do so he wasn't sure. I then asked him if he actually didn't want to see me, and he said that he both did and didn't, and that he wouldn't go out of his way to see me. I understand this, he is still angry at me. I knew he would be, but it is so hard. I still love him and I want use to get back together but I don't know how.
Should I be thinking about us getting back together? Is it unrealistic to believe it could happen? Should I give it more time or had 7 weeks been enough? Or should I try to forget him altogether and move on?
And, more generally, has anyone else gone through something like this? What did you do?
I don't know what to do, so any advice is much appreciated.