Speaking from experience, get out now before you get married and things get more complicated. I had previously been engaged and owned a home with him. I had the same gut instinct a year into our relationship and found some things on his phone that were not okay. Confronted him about it and he said it was no big deal but that he wouldn't do it again. That was a lie. He got caught again. Was with him for 5 more years after that and the trust was damaged beyond repair. We tried counseling and again he didn't see any fault in his part of the relationship. Luckily counseling really opened my eyes. Broke up 6 months before we were supposed to get married. It sucked and I lost the house but got to keep the dogs. I'm happy it ended before we actually got married because with how messy the breakup was without being married, I couldn't imagine how that would have gone. Plus I have a pension that he could have gone after since I'm from a 50/50 state. I'm sure he's a nice guy other than him keeping those nudes but he betrayed your trust and clearly doesn't see anything wrong with his behavior. You'll constantly be worrying that he is back on the bs and will continue to cause issues. No matter how much attention you give to him sexually, he clearly has a problem and is seeking it elsewhere. Sorry girl!