Found out my husband did porn

I've been with my husband for 5 years and he never once told me his did porn. I don't consider porn cheating but I just don't like it in my relationship. He knew my feelings about porn but never told me he himself did porn. I found out from his sister. Him and his sister don't have the best relationship but she randomly asked how I felt about my husband's past in porn and I said I never knew. She told me where I could find his porn. In order to find his I actually had to search a different porn stars name because I'm assuming my husband wasn't a "famous" porn star. He was just there. But I found it on a gay sight. She wasn't lying... It was mainly torture and humiliation BDSM type stuff. I was hurt and angry and confronted him and showed him so he couldn't lie. He's refusing to talk about it. He said he was 18-21 and it was the most traumatic 3 years of his life and he's not talking about it. He ended up cursing his sister out because he's pretty sure she did it on purpose to make us fight. So am I just supposed to let this go?