Long story short... would you trust him?

So my boyfriend of 6 years and 2 sons together, started seeing this girl behind my back for months. During the months they where together, she fell pregnant, and didn't tell him, so he didnt see or hear from her for 9 months. But then when there daughter was born and he got the DNA results back that she is his daughter. He was back seeing her behind my back again for weeks when she moved into her new house. Which isn't far from mine. I thought he was just calling in to innocently see his daughter but he wasn't they where together.

So anyway, they ended up breaking up and he wasn't seeing her for another month and a half. But unbeknown to me, he started seeing her AGAIN, behind my back all of last summer. I spoke to her and she said hes telling her he's in love with her. And dosent know how to end things with me without hurting me. But he's going to sit me down and have a talk. Which he did do. So he ended it with me, and got into a relationship with her. Then at Christmas time while he was calling into my house to see our boys, we slept together and I ended up pregnant again. I purposely got pregnant to try and fix our relationship, and because she got a daughter that should have been mine. I wanted a daughter. But she also was pregnant the same time as me. He left me to the pregnancy of our daughter alone while he was by her side the entire time. He was at the birth of there second daughter. Wasn't at mine. And didn't come near me. Now, our new babies are 2 weeks old, and they have broken up. Now he's been licking up my bum, coming to my house everyday. Staying over. Taking us out. Phoning me. But what happens when him and her start talking again, yesterday he spent the whole day with her before coming to stay at mine last night. Would I ever be able to trust him. Will it ever work out between us. He will still be calling in to hers to see his daughters and that. I just don't know what to do.