Almost certainly the biggest mistake I've ever made.

I apologise in advanced if this is a bit of a ramble or hard to follow, I have an awful lot to try and write down with no real idea of an order, so I guess I'll work chronologically.

I met Sarah at a sixth form party, I was 16, she was 18, and we hit it off right away. Unfortunately she had a boyfriend at the time so nothing happened. About a month later they broke up and about 4 months later we started going out. She was my first girlfriend, first love, first girl I'd even kissed. The first year was brilliant, but I did get a bit carried away, as you do in the "honeymoon period" as they call it. Anyway, after about a year things started to calm down, I was doing my last year at sixth form and had been travelling to visit Sarah at uni most weekends. I started to think to myself that all the stuff I'd said about never wanting to be without her, being with her forever, etc, was foolish, because in reality we were both very young and the thought of my first girlfriend also being my last was not a pleasant one. I'd never been very good at being open and kept what i was thinking to myself for a few months until it reached a peak and I ended the relationship. The break-up lasted about a week before I started regretting it and we got back together.

The next year went really well. I decided to go the the same uni as Sarah and we had a much more adult relationship than we'd had at sixth form, going on proper dates, going on holiday, spending a lot of time pretty much living with each other. But again the same sorts of thoughts and feelings started to surface. I was more open with her this time and she was brilliant, she suggested giving me a bit of space, cutting down on the talk of the future, etc. Nothing really worked though. And I hate to say it but I became a pretty shit boyfriend, distant, un-romantic, making her feel like my mates and various other things came before her, and I even started flirting with other women and kissed a few. Despite all this she still stayed with me, and was amazing. From what I remember she never did a single thing wrong, maybe I'm seeing it through rose tinted glasses. Even with all this it still reached a point where I ended it. We'd been together about 3 years at this point.

About 2 or 3 weeks after the break-up Sarah asked me if I would come round and have a talk about everything, I agreed. We lay on her bed and talked for a little bit, then we started hugging, and before either of us knew what we were doing we were having sex. Not the best idea, especially on my part. Afterwards we had a long talk about us, about my phobia of commitment, and about what had just happened. With all the thoughts and feelings that had prompted me to break-up with her still fresh in my mind I was very against giving us another go and we decided to leave it at that. However over the following 3 months we continued to sleep together. I know I was being incredibly stupid and selfish by letting this happen, I can only imagine what a roller-coaster it must have been for Sarah, but whenever I raised this with her she assured me that if it was making her feel worse then she wouldn't be doing it.

After about 3 months of this going on I realised that I still had feelings for her, strong ones, but I was also very aware that this had not stopped me breaking up with her twice before because of my commitment issues. We had a good long talk about this and decided that we weren't going to get back together, but if we were both single in a few years time after uni then we should give it another go, we also decided to stop sleeping together, because it wasn't helping us get over each other and because she was thinking about seeing a guy, one of her elder brothers friends, that she had liked for a very long time, since before we had met. She started going out with this guy a few weeks later.

It's now been about 8 months since the break-up. We still see each other fairly often, 3 or 4 times a month, and are good friends, able to have a laugh and a good time in each others company. I thought for a while that I was almost over her, despite having a few moments where I missed her a lot (I assumed this was natural), the other night I found out this wasn't true. It was Sarah's birthday and she invited me to go out with her and her mates and her current boyfriend in town to go drinking and clubbing. I was a little bit hesitant about it being awkward, but she assured me that he didn't have any problem with me and that I'd get on with him, so I decided to go. She was right, I did get on with him and it wasn't really awkward, but it was also a lot worse. When I saw the too of them together, kissing, hugging, flirting, it was incredibly upsetting, and I mean properly heart wrenching. I stayed for a few hours but in the end snook off early without saying goodbye. Since then I've been unable to get her out of my head, when I go to bed I can't stop thinking about cuddling up to her, I check her Facebook profile all the time and feel like I may have made a huge mistake. I had thought like this on occasions over the last 8 months, but now it's constant.

I'm not really writing this asking what to do, because I know what I'm going to do; nothing. I broke her heart, caused her so much hurt, and now she's got a happy stable relationship with someone she really likes. She's been far too kind to me as it is, I wouldn't blame her if she hated me, but she doesn't. I know I can be horrible at times, but I couldn't bring myself to interfere with them and how happy Sarah is, after all I've put her through. Even if I did and somehow manage to get her back then there's the chance, it's happened twice before, that I'm just going to freak about commitment again and end it. I suppose the reason I'm writing this is to get it off my chest and to get other peoples opinions on it. If you've read all of this then I really do appreciate it, even if you do think I'm a b***ard by this point, I certainly consider myself one.