I’m ashamed to write this because it has been shocking to me and I’m not entirely sure what this is or if it’s a betrayal from my husband or what..

My husband has a fetish and he did not tell me about it until we were married for close to 7 months. I had no idea about it but I have been fine with this fetish and never judged him for it (cause it’s really not even that odd). But anyways he confessed to me that while we were dating/engaged he was ashamed of this fetish and used to talk to people on Reddit etc to express this fetish and never told me. But says he realized that once we were married it was worth telling me about it and that he stopped using others to express this fetish... now my initial reaction is to feel upset and feel like I’ve been betrayed. But he’s assured me it’s been 5 years since this happened and the only reason he didn’t tell me was because he was ashamed.. This did not turn into an argument and he didn’t seem to act defensive and was very open with me about it and told me he would go to therapy with me if I wanted to do that. So I do feel like he’s telling being honest with me. But I’m just wondering if other people have experienced anything like this and how it was handled? Am I over/under reacting? Any advice from anyone? I know I probably sound naive and my first instinct is to run when this type of thing happens because of my family history and having a dad that cheating on my mom repeatedly. So I’m just here to vent and see what others say