Advice Needed

Sa
Ladies - I need some advice from an outside perspective. I get it from my family and friends but I already know the advice they're going to give before they give it, so I just want to share what I'm going through and see what advice you have to give. 
I'm 39 weeks pregnant and my boyfriend and I live together. We purchased a house together a year ago and our baby was planned. Now, I guess I really can't even call him my boyfriend anymore because we aren't "together". We hit a rough spot shortly before we found out we were pregnant and we've tried to recover but our communication styles are very different and since January, he moved out for a couple months, and our break certainly didn't bring us closer together but only farther apart. He moved back in in April and I'm still trying to figure out why he thought it was a good idea to move back in when we aren't on the same page. He's been emotionally and mentally abusive so I have a hard time standing up for myself. We still have sex and right now we are on civil terms. In the past few weeks, I was starting to think that our relationship was improving and heading in a good direction as far as being good co-parents, because I honestly don't know that things can be mended between us otherwise. I very much would love things to work and I've been trying to put in effort and show commitment but he seems checked or often and we definitelya aren't on the same page. To be honest, I don't think he knows what he wants. Anyhow, he left his phone lying around and I found he has a Tinder downloaded, he was snapchatting an old friend, and he's gone crazy "liking" girls selfies on Facebook. I know it sounds silly and immature (believe me I do) but on the reverse, I think it's immature that he's acting this way when we're about to have a baby. My main thing is that he's being completely disrespectful. He made the decision to move back in and if he wanted to act this way, I feel like he shouldn't have made the choice to come back and live with me. Of course I was hurt when I saw those things but my curiosity was at a high and it's almost like I wanted to find these things so I can see that he's an ass, get over him, and just move on! But we all know, it's not that easy. So,  my question is... What do I do now? Do I confront him with what I saw and how I'm not comfortable with it? Do I let it go and just reject him next time he asks for sex then explain to him why then? I'm struggling. It's hard for me to hide my emotions and I'm trying to avoid an argument, but it has hurt me. I don't think that he's seeing anyone intimately but giving other girls attention when I feel like he should be focused on our baby and improving our relationship should be a priority. Your advice is appreciated. Thanks in advance!