I really like him and apparently he likes me too, what should I do about this?

I have had a crush on one of my best friends for a while now. We've only really been friends for about 4-5 months but we've gotten so close and hung out almost every day, and in that entire time he's never made a move or done anything remotely suggestive of liking me (however I have picked up on his emerge). Anyway, he has a girlfriend (who is very controlling, might I add), so I decided to leave my feelings alone and just be friends. The other day he was at my house and he was talking about his girlfriend, and the fact that they want such different things in life and he just doesn't see her in his future, so he was trying to figure out how to end that but let her down easy because he doesn't want to hurt her. Later my mom drove him home (without me), and she basically asked him how he felt about me, he confessed that he has feelings for me but wants to let his girlfriend down easy, wants to strengthen our friendship and sees me as being out of his league and thinks I'd never see him that way. So, I don't know what to do. He said that either way he needs to break up with his girlfriend but I don't want to take advantage of that fact, and I don't want to rush anything. But I want him to know that I am not out of his league and that he does, in fact, have a chance. How do I go about this?