Need husband advice...

Jayme
So have this hunch my husband is texting/talking to/possibly seeing other women. We have 4 kids, which none are his biologically, but we are 30 weeks pregnant with our first baby together. We've been married a little over a year and in the past he has hit up old girlfriends and chicks he has on his Facebook. We separated in July (3 weeks after finding out we were pregnant) due to him messaging an old girlfriend and me finding out about it via the phone bill. He denies he's ever cheated besides just texting these woman, mind you he's told them he wishes he could see them or meet them in person and the messages are late at night. We got back together in August with us both agreeing to give this marriage all we had. Well come September he was messaging this chick from Colorado and his excuse was she was really sick and he was there to be her friend but she sent me the messages between them and he told her he felt special she messaged him back, he wished he could meet her in person, he was used to sleeping alone, he was falling out of love with me, along with some other things..mind you he's told me they've been friends for awhile..BS..so I have been having this gut feeling he's back at it again. He has a lock on his phone, the phone is attached to him, he supposedly deleted all social media  (which he's still searchable and profiles are available to view on Twitter Instagram and Facebook), when he gets a notification on his phone the content is hidden, when we fight he leaves the house for the night or even days, he will shower twice a day (which isn't normal for him) and when he showers at night he will put on cologne then go get cigarettes but be gone 30 minutes to 2 hours. I have no social media but my sister did check on Saturday and she sent me the screenshots of his profiles. I just wish there was a way to truly catch him right now because I know if I found out he was hitting up other chicks, I would leave in a heartbeat because my kids and I don't need it. But I don't believe him yet want to that he is changing and being faithful. Any advice?? Please don't be rude and say I should've left way before now...if you haven't been in these shoes please be considerate and try to be understanding.