What should I do?

I found pictures of my fiancés, you know, on his phone in his "recently deleted" album. I don't think he knows there's an album like that on his phone. I asked him about it but didn't tell him I knew about the recent pictures. It's killing me inside to think he's sending them to some other broad. How low do you have to be to ask for shit from an almost married man? It's making me sick to my stomach.