Replying to Really into this girl...

So I'm really into this girl that I'm pretty good friends with but she has a boyfriend and they've been dating for a few years. I'm better than him at like everything but he could probably beat me up. I think that she is somewhat interested in me and has been for a while and I want to get her to break up with her boyfriend so that I could date her but I'm not sure how to do this.. Any advice on shit like this is appreciated.