I can really feel for the both of you, as I have been married nearly 30 years as well, and we have had to manage similar to you. We had been married maybe 8 odd years it's hard to remember back that far, and I had never said a word about my past. I had never said a word to anyone not one soul. I was starting to fall to pieces and then told him. For me it was a disaster. I don't think what I went through would happen to many. Will I hope not. But when I told my husband our best and most closest friend and his wife was also there and the next night we went out and I have no idea what had got into him ( maybe he thought well it's happened before so why not again ) but he locked me in a room and did to me what I had been through as a child, so not only did my husband find out about my past but had to deal with his very closest friend doing unthinkable things as well. It was a very big shock for him and I felt terrible.
I felt like I had betrayed him, I felt dirty, I felt like I had lied to him our whole married life, I felt I wasn't the person he had meet and fell in love with, I felt like a terrible mother to our children, I felt I had lost him his very closest friend that he had grown up with, as if I hadn't told them that wouldn't have happened that night, we haven't spoken to any of that family in over twenty years, I felt I had let him down so badly. I asked him for a divorce as I said I was to dirty and not the person he had meet and married. We had a very rocky couple of years, not because he was mad at me but I was such a nightmare he was angry at my childhood abusers, he was angry and betrayed at his best friend. We had a lot going on.
I have only told you this because, it always has two sides. I really feel for you as I know what my husband went through and is still going through 20 years later he still holds anger for those people, and still struggles everyday with all of it. On the other hand I can relate why your wife didn't tell you as I did the same thing. I really don't think she did it on purpose or to hide it from you. When it happened to me I turned into lots of parts and those parts just get through life as best they can.
I never thought I won't tell him because I want to hide it from him. It just all seems to blend Into one another, you just seem to push it into the back of yourself and do what you need to survive. All you seem to do in life is to survive. That becomes the soul purpose of your life to try and keep going, whatever your poison as they say, drinking, drugs, workaholic, disassociate, there are two many to mention, then after so many years of doing that it just becomes part of you. You don't stop and think you build a web of trying to survive lying to cover your tracks not telling family, parents, friends, co workers, nobody. You get so used to hiding your dirty horrible past that it just becomes so automatic it goes into a part of your brain that not even you wants to know about. I didn't do it on purpose i have no idea why but it was tucked up so tight inside that I couldn't even deal with it so just put it into another part of me. A part that I didn't even know how to deal with.
I am so sorry you are going through this and I really feel for you on both levels. I am sorry I haven't got any magic answers, but I just wanted to let you know that you are not alone and I wish I could help you more.