Boyfriend Drama

So me and my boyfriend split up for about 4 months back in May. Of course, we each started to see other people, but we ended up back together here in the last week (I'm pregnant with his child after a weeks visit about a month ago...long story short, we tried to see if we could work things out).

Anyways..before we got back together, he was still texting this girl he had hooked up with multiple times, and I told him that needed to end when we got back together. Well, I caught him texting her again THE DAY I MOVED BACK IN 🙄

Well, I confronted him about it, and he said to give him a couple of weeks to end things because they were still friends and he didn't want to end it on a bad note (I rolled my eyes sooooo hard at that btw). Well tonight, I caught him again messaging her and I told him I wanted to see the context of their "friendly" texting. He agreed to show me, but wouldn't tell me his passcode to get in his phone. He said I wouldn't like what the messages consisted of. Like wtf.

So I asked him why he would text her like that if he knew I wouldn't like it. He basically said "because I'm doing me for a couple of weeks". Ummm. Okay. Then I told him I didn't trust him with her, because he's cheated on me in the past. And he told me that if I didn't trust him, he's kicking me out once I have the baby and he's going to keep it.

I am absolutely at a loss right now with the way he is acting. Am I completely overreacting or should I keep my distance for a while? I don't want my child to be taken away from me, but I also don't want to raise a baby on my own.