My life and how to avoid my problems

This is basically my friend life:
So it all started last year when my BFF, Rebecca, moved into the neighborhood of my other BFF (at the time), Courtney. The next thing I know, Courtney and Rebecca are BFFs too, which is fine until they started to talk about... Me. And let me tell you, it was not good things. They were having fun little cats about how "bossy" and "mean" and "controlling" I am, and, hello, Rebecca is SO much bossier and controlling than me. Her motto is "My way or the highway", like are you kidding me? Well, this year, Rebecca has been acting differently. She has been treating me like dirt, never saying sorry, screaming at me, and generally being a jerk. When I tried to stand up for myself, she cried and started talking to the teacher. She throws me under the bus for everything and acts like a victim. She knows that Someone has to take the fall for her mistakes, so she thinks it should be me. She also does everything for attention. recently a friend passes away, I have been feeling sad and depressed and sometimes wanting to harm myself, and all she does is make things worse. I just a few days ago left her and I am already feeling a huge weight lifted off my chest. Welp, I'm done venting now. On to advice!

Advice:
If you have a friend like Rebecca/Courtney, here is what to do:
1: Talk to someone you trust. maybe a parent, counselor, or friend
2: Remove yourself from the toxic relationship. I promise you will feel better up and out of there
3: Something about how to avoid what happened to me: if you notice a friend acting up, bring it up right away. I waited so long that it became worse.
4: talk to a counselor/therapist WITH your friend. If you understand each other more, maybe you will be able to fix the problem.
5: Try to stay positive and kind to the other person if they see you acting well, maybe they will too.
(More advice coming soon)

HOPE YOU ENJOYED IT!