My boyfriend living a double life

I just want to say, I have a 2 year old with a different man. I started seeing this guy in July of 2022. We got pregnant early unexpectedly in September. Well, I just found out in the worst possible way, he’s living a double life.

We had broken up about a week and a half ago due to me having a gut feeling he was cheating & not being there for me emotionally, and I went and seen him to try to fix things, I woke up the next morning, and while we were intimate, HIS EX WALKS IN SCREAMING. They dated for 7 years on and off, because she cheated. She started screaming and pulled up messages of them talking since October (while I was pregnant). Apparently they’ve just been texting/flirting through text. Then the day I broke up w him (1.5 weeks ago) he invited her over that night and slept w her. He told me, he doesn’t know why he did it. He felt left hanging when they broke up, but he loves/wants me. I feel like I have PTSD from seeing all the truth come forward, and I got manipulated into thinking I was a problem for following my gut. He’s never cheated in his life, until now. He wants to move forward, but I feel traumatized. Everything was a lie. We lost our baby, and he looked at her. While I had Christmas with him, he was texting her. It hurts, and I’m confused as what to do

He said he doesn’t like her, and he realized it when she left his house and everything had already been done. I’m lost