He cheated..

My fiancé got a call the other night at 2am quickly declined it I tried to call back they picked up and said nothing. He swore he didn’t know who it was. I found out myself the next morning and confronted him. He claimed this girl had been calling him he kept declining her calls and wasn’t talking to her. I reached out to this girl NICLEY and she was being extremely rude telling me she didn’t owe me shit. I went through our phone records and he’s called this number at least 20 times the last 2 months. We just had our first daughter in may. I started to notice more numbers with multiple calls. He finally admitted and said sometimes he calls people( old girls he used to fuck) just to talk and catch up( boosting his fucking ego) his reasoning was that he feels like I’m going to cheat on him and he’s always so anxious. He said I make him feel weird about watching porn ( we’ve gotten in to fights because I try to explain it makes me feel uncomfortable and insecure he always agrees not to watch it then does it again.. anyways ) I never told him he was weird for that that I just didn’t like the way it made me feel and out of respect for me he shouldn’t want me to feel that way either. He says he’s never meet up with any of these Girls, he doesn’t flirt, and the conversations make him feel “ normal” he basically was telling me he’s all of a sudden scared to commit. I took my ring off and told him I’ll wear it when i feel he’s ready to commit. He insisted I put it back on and he still wants to marry me, he’s committed, he’s sorry blah blah blah. All the calls are under 5 minutes. We share our location and he’s always where he says he’s going to be. I believe he’s never met up with anyone. I told him he can clean up his act or we can be in an open relationship because I don’t want to split it’s his choice ( he knows damn well he wouldn’t want me talking to any other man) He says he’s going to get a new phone number so I won’t have anything to worry about and I’ll never have to deal with anything like this again. I haven’t slept all night because I just can’t shake this. I feel so betrayed, but I don’t want to leave him especially because our daughter was just born and it was just meaningless phone calls. But it’s been going on for MONTHS. What would you do.?