What should I do about my best friend?

okay so I have this best friend, sometimes she treats me like dirt and embarrass me infront of our group but afterwards shes like loljk i love you. she backstabbed me again for the 3rd time, she told somebody my secret that i didnt want anybody too know, then i confronted her then shes like idk. then we had a really big arguement i told her our friendship is over then she started too get really bitchy too me but like i didnt do anything. i don't want too be her friend anymore but i kinda have too because my 2 other friendds are in that group and idk if they will leave with me or not, i dont wanna lose them what should I do :(?