boyfriend cheated in May last year, still not over it

My boyfriend cheated on me last year and I found out in May (after I had a miscarriage). He was going behind my back with a girl from work and had swx with her while him and I were together. While I was pregnant and the day after my miscarriage. It took him and I months to get back together because he insisted for me to give him another chance. I'm still not over it though and it's February. Im pregnant with his kid again and this one seems sticky. We hardly had sex after what happened because I felt no desire to have sex with him and I still kind of don't. I'm not sure what to do. When he wants to have sex I think of him wanting to have sex with her. So I just make excuses to avoid it. Sometimes I wish I just left him and it makes me sad that I still feel this way. I feel really sad because he's so happy to be having a kid and he has been treating me really well but sometimes I wish I could just leave him so I could stop feeling this way. & then I feel jealous of all the women with faithful men and I can't even say that I have one. I don't want us to be fighting in front of our kid but sometimes I feel like I got myself into something that I shouldn't have. I'm so lost and pregnancy hormones make me even more depressed about it. He can't change what he did and I can't stop thinking about what he did. I feel like leaving and being a single mom if I can't trust him still. It's been almost a year and I still feel betrayed. I still cry like it happened yesterday. I never spoke to guys before I found out because he thought they would like me but now I realize why. Because he was cheating on me and thought I would do the same thing. He knew it was possible for guys to like me more than a friend and he was afraid of me doing what he did. I speak to guys now that I've been friends with for a while and I don't speak to them in a flirty way but I can't even think of him talking to girls. I won't allow him to because of what he did to me for so long. He was speaking to girls and hanging out with them behind my back for a year while I couldn't even respond to guys on Facebook. I feel like I would leave him if he spoke to a girl even as a friend because I do not trust him around girls at all. I know this is unhealthy. Has anyone else gone through something like this? What happened?