AITAH for not telling my fiance why I am sterile?

So I'm late 20s F and my fiance early 30s M Let's call him Carlos are still fighting about this and it was already two weeks ago. When I was 21 I had a partial hysterectomy due to adenomyosis. It was very painful and my doctor spent two years fighting for the approval because many people were against the idea. I didn't mind losing my uterus because 1. It was very painful and 2. I was always childfree even as a kid I didn't like kids. I met Carlos three years ago. I told him on day one that I was childfree and completely sterile. He said he was childfree too so we went ahead with the relationship. He proposed in September and we started slowly planning the wedding. I never told him about the hysterectomy itself. I did not hide it on purpose It honestly just slip my mind because I already told him I could not get pregnant. My mom did not know about the engagement because she was out of the country taking care of her elderly sister and I wanted to tell her in person, she came back three weeks ago. After she rested for a week we invited her to lunch so we could tell her about it. Carlos is a prankster but mot the weird kind, while we were eating and before I could show my mom the ring he grabbed her hand and said I am sorry Mrs Mymom I impregnated your daughter my mom burst out laughing, looked at me and said either you are about to get rich or you grew a new uterus. I laughed too and said I hoped not because I had to talked to half the doctors in the country and their grandmas first time. Carlos stared at me and said What do you mean. My mom said The hysterectomy of course. Carlos said he had never heard about it. My mom laughed again and asked how he did not know. I said I guess I never brought it up because I do not think about it anymore. We were quiet for a second then I showed my mom the ring and we celebrated. After she left Carlos confronted me he asked why I never told him about the surgery I told him I had told him the important part which was that I was sterile. He said the issue was the principle and if I could keep something so big to myself for years what else could I hide. I feel like that is unfair for me I shared the relevant part at the moment and later I just didn't think about it, I was not trying to keep secrets I simply didn't think the medical details were relevant once we already agreed on being childfree. So now we want outside opinions. AITA for not telling him about the hysterectomy or is he overreacting. He has read this post and approved it so this is not only my point of view. I came back and there were soooo Many responses I'll make a quick edit to clarify some things How did you forget to tell him this: it was a very traumatic experience and everyone and their mother looked at my vagina (uterus actually) I felt embarrassed for a long time and pushed the experience deep enough till I forgot about it. Why didn't you tell him? At first because I wasn't about to trauma dump on a dude I known for 2 hours and I'm just a very quiet person in our first date I said maybe 50 words I'm more talkative now at least with him but I like my privacy and to keep things that feel deeply personal just to myself unless is relevant to something