Feeling guilt for liking a guy

I am a guy 17 and homosexual. It is very secret that i like guys (i have only been with girls before). In school I take physics with the grade above, and we have been working on a big assignment for over a month. The guy I am paired with is really kind and handsome, and we have become pretty good friends. But I have also started to like him in a romantic way. I hate it so much, I wish I could just see him as a friend. I feel so guilty, because I can imagine how disgusted he would be if he knew (he has a girlfriend and all). Has anyone else felt something like this?