I really hate my "Friend"! Advice?

So i have been friends with this girl for 6 years! I gave her what i thought were the best years of my life and so...Well the stories long i will begin now! So we were best friends till about 3 years ago she became best friends with a new girl sophie she was mean to people and became the leader of our group. That wasn't a problem then but then 2 years after she started being mean to me and my other friend ellie and then we became friends with this girl Lets call her chloe so we all became friends with her. Then about a year after that we all loved eachother but sophie had left the school so again we all got along but then the one i had been friends with for 6 years started ignoring me and ellie and trying to impress chloe and she was SUPER mean to me and ellie and now we absoloutly hate her so what shold i do!