How do i forgive myself?

I am 19 and i broke up with my boyfriend seven months ago. I was the one who initiated the argument because i just felt so suffocated in that relationship. I have anxious attachment with abandonment issues and parent issues. Oldest daughter in a brown household.

So my ex was extremely attached to me. He never wanted to let me go. Even when i would ask for short breaks like 2 or 3 days he would absolutely deny. But he was very nice to me. At least on my face. Behind my back he did a lot of sketchy things and microcheating too.

I was extremely toxic in that relationship. I would bring up the same issue five times to argue about it. I would threaten to break up with him. I always wanted to leave. I never got over the things he did that disrespected my boundaries and slowly the resentment started to build. Which later on reflected on how I treated him.

But my ex would always come back. After every argument he would be back in the morning all so happy trying to fix everything. There were times when i went back too. When i apologised too. When i tried to fix things too. But he did it more number of times. Until the last argument where he had enough. And didn't come back. Within less than one month of breakup he lost feelings for me.

Its been seven months since the break up and every single month i have reached out to him begging him pleading him to please give me another chance. So that i can do everything right this time. However he has denied it everytime.He is just stuck on the fact that he doesn't want a relationship ever again. I know with me is silent

Currently we are in strict no contact and he doesn't want to talk to me ever again. He told me he started hating me. He also likes someone else. But for some reason i just have this very heavy guilt and regret. The main reason why i can't let go him is because i just feel so so so regretful. I want one last chance with him to treat him right this time.

Please give me advice as to how do i forgive myself and let go of this guilt and then finally move on.