Partner (22M) cheated on me (20F) all along because i have trust issues?

Hello! so I (20F) have been in a relationship with this man (22M) since I was 17. It has been almost 3 years together. I cannot lie, I have always struggled with trust because the only relationships I had been in before him (little, insignificant ones, but you get it) have been tied with unloyalty when I have always been loyal. For this reason a few months into our relationship when I was still 17 I started to struggle to trust him and struggle with jealousy. Even though I had been cheated on before I had never felt that in a relationship, I guess it could be related to this one being my first serious relationship. He was controlling about who I am around and what I am wearing since the start, and I guess I picked up on it and started having a lot of boundaries regarding other women. We both agreed 100% that watching p*rn or other women while you are in a relationship is cheating. Nevertheless I always doubted his trust and it did get a lot better the past months. Like, a lot. He has physically assaulted me and kicked me out of our place whenever he wished to (we have been living together since almost the start of the relationship). This has been going for a year and a half and he always accused me of cheating. A few days ago we were fighting and he smiled at me and said that he has always been smarted than me because he has been cheating all along and I had no idea. He goes back into work and on call I beg him to elaborate. He tells me during call that for the past year and a half he has been watching porn and looking at other women, on the street, pictures, everything, because he had so much hate towards me that he needed to put it somewhere and “it was either drinking himself off, cheating or hitting me” and the last two he has done. He also thought I would not forgive him so he did download a dating app literally a few days after a breakup and now he is telling me to understand him. He chose a less popular dating apo because he knew my best friend was on dating apps and he didn’t want to be found. He had no matches.

Please tell me your opinion on the situation… I feel super confused and hurt.

TL;DR! - partner cheated on me because i had trust issues about him being loyal to me and is telling me to understand him because he had anger towards me