Best friend problem please help!!!!!!!!!!!!?

[Shopping_Princess]

Ok so i have a really close friend like a best friend and she has friends she hangs out with. I used to hang out with them until my bf's friend stoped liking me cuz she thought i was givin her attitude even though i wasn't and she even tried to get my bf away from me by tellin her that i gave her attitude. I HATE MY BF'S FRIEND!!! She gives me hella attitude. and now even my bf has started to give me a little attitude like when she is with them she ignores me and gives me attitude but when she is with me she is the same. I told her this and she said that she hasn't changed but she has!!!!!!!!! Everytime i try to talk to her about it, she kind of starts yelling and tells me" What is your problem, tell me to my face!!!!!!" Ugh! She pisses me off sometimes. But later she gets cool again. Do u think she changed? And what should i do? should i stop being her friend? or talk to her or send her an email. Just tell me what i should do plz!!!!!!!!