Sorry if anyone as already asked this before or if there's a similar thread. (I'd love to see it)

So, I (30F) got out of a pretty horrible situation with a NEX - I was gas lit, cheated on, mentally and physically abused, and stalked. I was with him for about 2 years, about 2 years ago. Since then I chose to be single, work on my BPD and self partnering. 

Then I met my current partner(28M). He was so understanding and loving, he understood my BPD, my trauma bonding, and was so good with communicating. We have been together now for about 10 months now. Any time I felt weird or that he was going to leave me/cheat on me, we would calmly talk about it and he would reassure me.

About 5 months into the relationship my old ways of thinking were getting the better of me. I was waking up in panics, I was obsessed with wanting his phone. I just thought it was because of my history. But one morning I woke up and just grabbed his phone. The first time I had ever looked at it. 

He had been talking to one of his exes, he was having a online only relationship with another woman who was sending him nudes and they would text out sexual fantasies of each other(which he ended 4 months into our relationship), and he has lied about another woman he was trying to ghost but not telling me. He promised me over and over it was just us. He has since stopped talking to all of these people, he tells me everything now. We had a huge heart to heart, its been 3 months of truly rebuilding and during this quarantine he have gotten a lot closer. 

I just wanted to see if anyone has any advice for letting go of being cheated on (I cheated on others when I was young and I learned to stop). I know people can change. 

I'm asking here because I have such a hard time obsessing. And I would like to make this relationship work. There is a lot of good.