Help! The guy I like has a girlfriend and we did stuff. points for answering?

You need to dump the guy. I'm sorry that that happened to you and everything but it seems like you got played and it turned out bad. No decent guy would do that to you. That girl is probably his girlfriend and you don't want to end up in a lot of drama. So you'd be better off without him. You'll find someone else better and more deserving of you. Also to keep yourself from hurting again, avoid sleeping with the guy.