He told me his ex was tighter

A little background, me and my fiance have been together for five years and I'm four weeks postpartum currently. He knows I've struggled with how I view myself in the mirror and often tells me he loves my body when I get in those moods.

I'm two weeks away from getting the all clear from my doctor so he's been talking about what kind of sex he wants to have when it's time. Well the other night, he asked me to be honest and proceded to ask about my exs' dick sizes. I said I honestly didn't remember and didn't want to talk about that anyway but he wouldn't drop it. I said something along the lines of, "I'm not going to lie to you because I don't even remember". Which I dont, I've been with him for 5 years and most dicks look the same to me tbh. I know I should've just said he was, but I was annoyed he wouldn't just drop the subject. So I tried to make a point and asked how he would feel if I asked him about sex with his exs' and how tight they were and if that would make him uncomfortable. Without hesitation, he tells me how he's been with people tighter than me.

Well it's been a couple days now and I cant get over that comment. I feel disgusting and the thought of us having sex again at the 6 week mark makes me terrifed. When I bring up that it's bothering me, he just gets defensive saying he just said that because of what I said.

I know I'm in the wrong for not just saying he was the biggest and then for asking about his exs' to prove a point. But this is hurting me really bad for some reason. How would you move on from this?