Honestly I really need advise here?

I am totally in love with a girl...but she only likes me as a friend. I cant really back off or de-friend her, because her boy friend de-friended her when she broke up with him and now she thinks he is a total jerk. but I cant stay friends with her, cause the more we talk...the more I love her. I have never liked a girl this much ever. what do I do?