Very confused

I'm currently 22 weeks pregnant and I feel my fiance so distant. The other day I was using his phone and he got so jumpy. He jokes a lot and has some insecurities from his previous marriage. A few days ago I found some YouTube searches for girls in underwear. When confronted him, he said it was a normal thing and that he was looking at it because I don't wear sexy stuff for him. I feel fat an unattractive, my belly always get bigger so I have no interest in being sexy. What should I do? Is it a normal guy thing? Is he cheating or wanting to?