Left a pretty toxic situation and I don

I really want to get this off my chest and just ask for advice or whatever, Im not really good at these kind of things so please bare with me. For the past 7 months Ive knowingly been in a relationship with someone who was in a long distance relationship with someone else. There was a time where I made him choose and he went with her and then the next day we got back together...few months pass and other shit happened and he told me he broke up with her...which was complete bs. In the whole time we were together he would get hella possessive of me and would get mad when I wouldnt give him any attention. Later on in the relationship I found out he slept with my best friend prior to us getting together. I was hurt, I constantly asked my best friend about it and she always lied to me. For a while I didnt talk to her because I was so mad at the whole situation and after that our whole friend group broke up. Fast forward to this month, I get a text from a friend saying that this dudes gf knows bc someone DMd her on anon and this guy chose to end things with me for a second...and then said we can finally be together like a legit couple.