How to deal with toxic friends?

So I have two friends lets call them Anna and Karina.

I've been best friends with Karina since Kindergarten and sometimes she's the greatest friend in the world and other times she treats me like ****. In third grade she ditched me for new friends and would bully me and purposely leave me out of stuff. I forgave her though because I was young and stupid and she keeps doing it and for some reason I forgive her. I think it's cause I've been her friend for ten years now and I don't want that to go to waste. I'm very shy and don't have a lot of confidence while she's way more outgoing and has way more friends than me. When she's around her friends she completely ignores me. What should I do? Should I just cut her off completely? My other friends say they don't like the way she treats me.

The other girl Anna I just met last year in my freshman year. Recently she just reported to the principal I was bullying her when it was for from it. We had a trip a few days ago and me and Karina and our other friend were goofing around on the bus and pulling each other's hair and poking each other. We did it to Anna because she was with us and she got really angry. I realized it was stupid and maybe Anna took it the wrong way and I tried to apologize but she won't reply to any of my texts.

She pisses me off though because she acts like she's this perfect little angel who gets bullied when she's far from it and actually a bully herself. She's mean to everyone and always points out their flaws. I used to be her best friend until she started calling me names and telling me I was too skinny and I needed to eat even though I ate a lot in front of her. I'm naturally skinny and putting on weight is pretty much impossible for me. She's into partying, drinking, hooking up etc. and I'm not and she makes fun of me for that. She makes fun of the music, movies and TV shows I like. She also treats her family horribly she's so mean to her little sister who is the sweetest most adorable little girl ever. She calls her mom names like b*tch and c*nt. She's had boyfriends that say she should treat her mom better and she gets mad at them for it. She met this one boy on kik who broke up with her to date his friend who just so happened to be black. And she said "ew a black girl and white boy dating is disgusting".She calls her sister a **** even though her sisters white it makes no sense. She shouldn't call anyone that regardless. And she's also homophobic. There's this one girl at my school who's a lesbian and she was like "omg did you know Olivia is dating a girl? That's disgusting". I go to a catholic school and she always goes around saying God isn't real and religion is stupid. I'm not Christian myself but I know a lot of people at my school obviously are. I don't want to be her friend but I also don't want to be mean to her or end on a bad note. What do I do?

I'm fifteen and a Sophmore if that helps.