What should i do if my friend is being a brat and stealing my other friends and they're on her side?

ok so i was at my best friends party and jessica(the mean one)was invited. so i didnt mind that my bestie invited jessica knowing i hate her.im not going to control her life. but then jessica took an other friend named kelsey into a room for hours. i was curious and so i was listening to wat she was saying. it turns out she was talking bull about all of us at the party. but still my bestie wants to remain friends with her and is mad at me for listeing to the conversation. but im happy about that because now i know who she really is. my other friends are willing to help me. they are the popular ones at my school, and they said i could hang out with them. they said that when i hang out with them it will give my bestie time to realize jessica is not a nice person.(they dont like jessica either). but what should i do if they dont like it when i hang out with them? who will i hang out with?