a word about best friends

The girl in the photo above is my ex-best friend. I say "ex" because the last time I talked to her is about 3 months ago. Last year, she was my best friend. I thought she was pretty, nice, modest, smart and funny. Now I think she is mean, rather violent, swears too much for my liking, arrogant, and she has a very high opinion of herself. she constantly sais how good she is at particular sports, how pretty she is, and what a great singer, actor, whatever. I now look at her and wonder how I could have possibly liked her at all.
Now I have many, many friends I would adress as my "best friend" azzy,aish,sophie.m,edi,mel,eli,taka,maya,jazz,and many more. best friend is singular, not plural. I'm not going to say whom I like most out of all these people; they're all awesome. however, the friend I've kept longest over my entire high-school life so far is jazz so congrats to her. I look at all my "best friends" now and wonder if i would ever come to hate them. I really hope not. I certainly can't imagine it. I don't think I even believe in best friends any more!!