What can I do?

I'm 37 weeks 4 days pregnant and ijust found out that basically my marriage is a sham.Well maybe that is overexagerrating...no..no its not.Me and my husband have been having marital issues as far as my trust in him.In the beginning I just chalked it up to pregnancy hormones and feeling insecure but 3 nights ago I got evidence and I didn't say anything because I wanted to just move on.But then I got curious and checked his phone the night after and saw a pic that was sent to him on my birthday that he saved which lets say didn't leave much to the imagination.I couldn't take it so yes I woke his *** up at 430 in the morning to confront him.All I got was an excuse that I was not even trying to believe but I was tired of crying and I just wanted my husband to hold me so we left it at that.So early this morning I check his phone and everything was erased but "somehow" I found more pics but I didn't say anything because I didn't know the dates they were uploaded.So I left his phone alone.Then I decided to google his *** and I found out he joined a singles website 1 month after we got married...3 days after we found out we were expecting a baby.Should I let him know that I know about it?its obvious that he has lost my trust completly.