Girl drama please please help?

[chloeloveslemondrop]

So me and this girl used to be best friends, and we did everything together and it was great. Until she started to develop a weird group of friends that all for some reason hated me and I didn't even know them. They told me to go kill myself and they would leave me out of everything and talk about me no matter how nice I was to them. Keep in mind that my best friend knew all about this and wasn't doing a single thing about it besides telling me to deal with it and that it wasn't her problem. I tried sticking up for myself but it just made it worse. My life was miserable. She tried to get all my friends to hate me and she joined literally everything I joined so there was no escape. Eventually, just because I was so depressed I apologized to HER. We were fine, until she and her little group of friends started being mean to me at school. She blocked me on all social media sites, deleted all the pictures of us on Instagram and calls me a bitch and an attention whore. Idk what to do.