My husband has been messaging other girls

I never get to see my husbands phone. It has a passcode on it and it's usually always in his hand. 
​In the past I've found out he was sexting another girl whilst our son was 2 weeks old, I forgave him and quickly chalked it up to "the other girl was lying" he still Denies it to this day. 
​On my honeymoon, I found a text to a girl saying I'll kiss your bruises better.... He said it was a joke because they both work in paintball but no I don't think u should joke like that when ur married.
​There's been quite a few things in the past and last night I was in the bathroom. 
​He stupidly left his phone on the floor and it said "chats" then a bunch of girls names under it. 
​I didn't pic his phone up because by the time I was about to he came in the bathroom looking for it. When I questioned him he said it was the screenshots of the apps aka when u go into the App Store and have a look at an app. 
​I had a look on the App Store this morning and I seen that whatsapp have the exact layout he was using last night and the screenshots didn't include any of the names I seen. 
​I've sent a message to his phone saying "liar liar pants are on fire, I know exactly what you have been doing and I want to know exactly who these girls are and why u are messaging them, now!" 
​He's still asleep in bed just now but he will say my hormones are playing up or something (14 weeks pregnant with second) and he will turn it back around on me like he usually does. 
​Can't help but feel it's my fault because we haven't had sex for about a month. I just don't want to this pregnancy,  we had a lot of bleeding etc so I've tried to steer clear.