Why do I dream of my abusive ex-boyfriend?

I was in an abusive relationship for 5 years on and off, (on and off as I kept trying to end the relationship but he kept coming and telling me that I was wrong, as I had seen many evidences of him dating other women, he kept telling me that I was mental, paranoid, and need hospitalising, he also ogled women and told me that men did it, I do not mind him checking other women, not ogling them. He did not call me, everything was on his term. he cried when I tried to finish it with him, he would not call me but he called his exgirlfriend in Turkey who he claimed to be married, he never got me any present but I found out he gave presents to his cleaner, (the issue is not what he and if he gave others presents but my birthday, valentine, christmas was never acknowleged for me. I have a son and he never even invited him to his house and he never bought him a present. not even a card.

I went to his history on his laptop and found out he was on sex dating sites, he had met up with many women, some contacted me to tell me.

I finally confronted him last last year and left him. He sent me an email, telling me that his flat feels cold, big and empty without me. I did not reply then but 3 month later I wrote to him and said that I was serious when I said that I needed space from him. He has not written to me since my last email 4 months ago.

My problem: why do I dream about him, I am doing well, I know confronting him and leaving him was the best thing I ever did not to mention protecting myself from catching any std he may contract. (he was also a bully and he refused to use protection), I could have caught anything from him sleeping with women on sex dating sites.

He never complimented me yet he had the nerve to point out women and tell me that she was beautiful, again if he complimented me it may have been ok, when I asked him why do you not tell me that anything is nice about me but you point out women and tell me she is beautiful, he told me that he did not need to tell me I was good looking. I am an attractive lady, I am being funny but I have previous relationships and I found it odd that he ogled women in my face from the moment the woman appeared till she disappeared as if I was his male friend and he would say she was beautiful.

He called me mental, when I told him how his behaviour made me feel. I used to be a confident person but with him I was an emotional wreck, I felt ugly and nothing. specially that for 4 years of our so called relationship I had gathered evidence that he was seeing other women. Yes, I know you are all going to say why did I take him back, he was a bully, he would hammer my door, I was scared, did not my son to get scared, I was weak. I finally got courage to tell him where to go.

By the way he told me that he regularly visited lap dancing clubs, he said he loved the girls, he told me it was normal for men to visit these women.

He suffered from premature ejaculation, he justified his visits to lap dancing clubs.

Why do I dream about him? He was never nice to me. In some of my dreams he is with other women, sometimes ogling women as he did when he was with me.

How can I help myself to stop having these dreams about him, have I not moved on yet?