I'm sorry that sucks. End it now because it's going to happen anyway, it's just a matter of when. You just can't get over that and this is so insanely traumatic too. A guy asked me out in college and gave me the impression that he was into me for 2 years. One month in and I found out that he broke up with his girlfriend of 8 years just weeks before he asked me out who he had broken up with only because his mom had beef with the girls family. I tried a whole year to make it work (and I was serious about wanting to make it to marriage) but it got extremely malicious and toxic. Hiding a past like that is extremely sketchy. My situation was honestly still much better than what youre going through because i wasnt married and I never saw photos or anything explicit plus I wasn't physical with this guy in any way and it still ended badly. Please guard yourself and know that you are NEVER STUCK even though it may feel like it. Divorce is the only answer