What should I do?

oh my god, i have the exact same problem...only im on the other side. I really really like this girl, and she feels the same way about me, but she has a boyfriend...it took awhile to figure out what i'm going to do, but if the guy is anything like me, and he really likes you the way you think he does, he'll wait...but i'm sure he'd prefere if you did break up with the guy, sooner than later....

You only live once. Don't settle. Go after the one you really want if you feel that is something you would really want in the long run.

-JP