Should I tell my best friend that I'm in love with her?

Well im Oscar (17) in high school and I have a best friend (17) in high school her name is Betty. We met two years ago and when we met, we became realy close friends. I went to a lot of dances together Homecoming and Prom. You name it, we do it together. She has helped me through so much and I do and will always do the same for her. Well for the past 4 months she has had a boyfriend who is good friends with me too. I have recently started having feeling for Betty wanting to be with her…I’ve fallen in love with her. But she has a boy friend. Heres the thing though. Betty talks more to me then she dose to him, she sees me more, and we hang out more like spend entire weekends together. Also a recent thing that happened someone told Betty’s boyfriend that it seems like Me and Betty are going to end up running away together, and shes going to leave him for me. Whe the boyfriend herd this he was realy paranoid to the point where I felt realy uncomfortable to even hanging out with Betty. I decided to keep my distance away from her…but she was willing to break up with him if it ment that I would talk to her again. Right now betty and her boyfriend are still dating but part of me wants them to break up and part of me dosent. I want to be able to tell her how I feel. But I cant. I dont want to hurt the kind of relationhip that we have. What should I do? Do I have a chance with this girl? Shoul I tell her how I feel?