idk what to do

I'm 9 months pregnant... about a month ago I found out my boyfriend had made a fake email and Facebook to talk to his ex girlfriend. From the messages I seen he didn't say anything out of the way but he still talked to her. I threatened to leave, but it's hard as I'm about to pop and rely on him. Then, 2 weeks later I find him on 'fuckbook.com' talking to other people/ sending nudes... I can't leave because my due date is in 2 1/2 weeks and I wouldn't have anywhere to bring my little girl home to. We've talked about everything and he seems to be remorseful about what he did but idk... I'm scared. We've been together for nearly 2 years now and nothing like this has ever happened. We've always had a perfect relationship. Before we got together I wasn't interested at all and he did everything in his power to make me interested. He seen what I went through in my last relationship ( it was mentally abusive ) So I'm having a hard time trying to figure out as to why he would do this to me. I honestly want to work things out so we can be a family but I have that thought in my head stating that he will do it again.. just like all cheaters do. He honestly seems like he won't do it again but like I said... I never thought he would do this in the first place. Relationships are all about forgiveness though.. right? Just give me some advice.. no bashing please, I already feel terrible especially with these crazy hormones.