I need some advice. adults only please!?

Well. Last night, I stayed up until my fiancee got home from work, which was about midnight, but shortly after he got home, I went to bed. We have a 4 month old together& I have no idea what time it was but she wokeup for a feeding. So my husband is so tired he falls into bed with his clothes& shoes on from work & left everything on in our living room. So I went to turn it off. His phone was on the couch. I looked at it& it was on a porn site but ALSO he was putting information in for finding singles, or as it said, "get laid tonight!" So instantaneously, I'm pissed off. I mean our sex life is good. I don't get why he would doing that. I DO have a right to be pissed off at him, right? Should I confront him about it or what? I had a dream last night that he had been seeing someone else& sleeping with them& it felt so real ! Idk what to do. Please help. I don't want it to destroy us, but at the same time, I want to know why he's looking at trying to get laid tonight ! Am I overreacting? Or do I have the right to be upset? HELP!