half my friends are like that. I hate it too. You should find someone that you can be really close with, and share your secrets with, since you can't really trust this person obviously.
I say don't be her friend because she most likley does it to you since she does it to everyone else including her other "best friends", she's in high school now and needs to grow up and face that being fake is going to get you anything in life, but drama. She's about to be a sophomore in high school and she's still acting like she's in the 7th grade.
your welcome,and you should probly tell her that you feel like you cant trust her and she needs to stop all the drama sh*t if she wants to be friends with you...i mean you only should say that if you feel tht way yanno??
she may be nice to your face, but she could also be talking about you behind your back. It's your decision but if i were you, i wouldn't be friends with her anymore. Even if she doesn't talk rudely about you, she's hurting other people. hope i helped. you can talk to me if you need to :)