I'm being led on and don't know what to do?

I've known this girl for a really long time, we went to school together and have been working summers together at an amusement park for a couple years. I really like her and she says that she really likes me. BUT SHE HAS HAD A BOYFRIEND FOR THE PAST 2 Years. She keeps saying that she is going to break up with him and that she wants to be with me, she also gets really jealous if i talk to other girls. I really like her, but I've been waiting long enough and i'm starting to get depressed. I honestly would love nothing more than to say "F you" and just get away from her, but I feel trapped because I work with her and I'm not to good at making friends, especially girl friends. I guess you would say i'm shy.... I have no Idea what to do. Somebody please help me.

I feel really silly writing this, but I guess somebody out there might be able to tell me something I haven't heard before or thought of.