Hey sounds like the same thing that happened to me man. I know how you're feeling right now. And there is no easy solution out of this because you do like her. The only real solution would be to forget about her, because even if she has feelings for you, she still has feeling for him. Thats not what you want, trust me. Unless she breaks up with her boyfriend, I'd try to just move on, that would be the safest route.

If you decide to try and get her, then be ready for what might happen.