Is it normal that i hate and love my best friend at the same time?

Me and my best friend have known each other for almost 9 years now.I met her after kindergarten,then we went to same school and we became like the best friends of all time! We've been through so much already but we never had a fight or anything.Anyways like two years ago she was this innocent girl who'd actually care about me.And now? Well,she kinda changed.When we hang with other friends she doesn't care about me at all.She slaps me for fun,when I tell her something She says she doesn't care,she bitches at everyone! Literally everyone!!,she always involves me in her fights with her friends and If i don't bitch at them or do what she says she gets mad at me and so much more stuff.It actually hurts me.This story may not sound too bad but it really does hurt me.The fact that she changed so much and became such an arrogant kid,hurts me.I'd love to talk with her about that but I think she wouldn't understand.She'd get mad and I'd lose her.But i can't imagine life without her.So basically because I can't talk with nobody about this I decided to post it here.what do you guys think? Is this normal? And I'd very appreciate it if some of you could help me and tell me what to do because I get so annoyed by her but i still see her as one of the most important people of my life.

Im sorry if there's some mistakes in this story but I'm on my ipod and I'm german so my english isn't too well.
Anyways,I'd love if you read this or commented on this.