What do I do?

Tonight I found out that my boyfriend of four years has been legit watching porn twice a day almost everyday. Apparently in bed next to me or my kids. We haven’t been having sex and he makes no attempts to do so. I also found pictures of naked girls that we both know that I have no idea how he got in his phone. I found out that on his Reddit account he was following swingers groups and singles groups in our local area. I’ve been reallyyyy struggling with postpartum depression and I just don’t know what to do now. When I tried to confront him over the girl we know pictures he says he doesn’t know how they ended up on his phone. It’s 1:30 am I can’t sleep and I feel sick.