How can I move on?

It's about 9 months that I broke up with my ex. He was an abuser, he lied to me, he left me several times with no reason and everytime, he flirted with one of my friends. He cheated on me with my classmates, friends, best friend and one of our professors. He made me to do the things that I hate, and now I hate myself because of what I've done.
I broke up with him the first time that i found out what a nasty person he was, but my best friend forced me to be with him again and that he loves me and this kinds of crabs. And months later, when he asked my best friend to have sex with him, she was not that angry, instead, they flirt with eachother a little bit more after that. But right now they don't talk to eachother, I guess.
Still, we are classmates in vertual classes and his voice bothers me a lot. It's been a year that I am living with my family and I miss my dorm and my roommate a lot. I think i am getting depressed. I have nowhere to go because of quarantine and I have to bear the voice of my abuser every week. And the worse part is that, some times i miss my ex.
What should I do with this mess?
How can I move on?
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