Can you give me some personal advice on being around a friend I have a crush on and his girlfriend?

Sorry about the length of this…

I’m in an awkward position. I attended two months of college in the fall of 2010 before getting ill and taking a medical leave of absence to get surgery. I don’t go back to college until January, but I’m already stressing about what it’s going to be like to hang out with the guy who was my best friend there during those two months. We had a bit of mutual attraction going on for a while, but in my absence he got a girlfriend and over the summer they traveled all over Europe together and they’re very happy together. I still had feelings for him when I found out about them, so I tried to just turn those feelings off. It didn’t work, though. I haven’t seen him for over a year and I still have dreams about him at night. Pathetic, I know.

We don’t talk often these days but he and others in our group of friends have made it clear that they want me back when I come back, which is nice. But I just don’t know how it’s going to feel to hang out with him now. It makes me very sad to even think about. I know if I want to keep him as a friend I have to be happy for him and his girlfriend, and I know I can fake that. I’ve already told him that I’m looking forward to meeting her. I guess what I’m worried about is that being friends with him at this point might be more painful than it is nice. I’m pissed at my disease for making me need to take time off from college because I think he and I would be together today if I hadn’t had to leave. Seeing them together will just make me feel that sense of loss a hundred fold.

All my friends there are his friends too, and I will probably be living in the same building as him too. I don’t think it’ll be easy to make new friends coming in in the middle of the year. So even if I did decide it’d be better to distance myself, it would be hard.

Can you give me advice on how to cope with these feelings, or anything I can do to make this easier? I’m trying to remind myself about the other fish in the sea…