Confusing teen prob. girl with boyfriend likes other girl with boyfriend.

Well, I'm 17. I have recently discovered I'm bisexual. I have told a few of my friends. I have a boyfriend. He is 18. He is bisexual also. One of my best friends is bisexual but she has a boyfriend.

I know I have feelings for her. But I'm scared she...

doesn't for me. And She's completely in love with her boyfriend. He treats her like crap. I don't want to screw up our friendship with my feelings. She always says she loves my friendship with her because usually girls freak out about her being bisexual and think she's always hitting on them. I can't talk to my boyfriend about it because I really do like him.

But I always feel this tension between me and her and it feels good! Every time she calls me or asks me to hangout or just wants to talk, I always smile. She makes me happy every time I'm with her. I love anything she does. I support her so much. I get nervous when I see her. I just don't know what to do!
Should I just leave it alone or?

and I feel bad for these feelings and thoughts in my mind towards my boyfriend but it feels like he isn't in to me. He never shows any affection towards me. We've only kissed once in a month. And we were kinda tipsy.

Well hun, the first thing I can say is that if you never tell your best friend how you feel, then you'll go your whole life wondering what would happen if you had told her. first you need to be there for her as a friend, and tell her that her boyfriend is no good for her. but don't just jump into telling her after she broke up with him. you don't want to be a rebound. you're better than that.
And if your boyfriend is bi, and never shows any affection towards you, maybe he's seeing someone else behind your back, either guy or girl, still unacceptable.how did he act when you two first got together? Look all I'm basically trying to say here is that you should tell your best friend how you feel or you'll feel stupid for not at least trying. You never know, she could be in the relationship with her jerk boyfriend because she's too afraid to tell you that she has feelings for you too, and doesn't want to get rejected and be alone. Good luck, and hope I helped at least a lil bit