Should I... Let this topic go

Hey ladies so months ago I made a post about my husband constantly talking about how I shit while giving birth and making fun of me for it. Constantly bringing it up. And my MIL had my back. When he was making fun of me to the family again and joking about it she showed me and everyone his old bedwetting chart from when he was 15. He apparently peed the bed until he was 16 and said I gave birth to a baby and what was his excuse. He ended up stealing it and cutting it up. Karma got him because same night he peed the bed for the first time in 10 years. Well... Now after he told me this thing I don't think it was as much of a joking matter as we made it.

So I had put the baby to sleep and he couldn't sleep so he ate and edible. His new meds for his bipolar make it hard for him to sleep. He then started talking about his cousins. I've met them. They've met our baby. He laughed and said "They used to fondle me when I was younger". I'm like "Huh?" He said when he was 5 they would jokingly fondle him but sucking touch his privates and having him touch them or lick their privates..... When he was 5 these cousins had to have been 18 or 19... I said "How long did they do that". He said "I think until I was 13 or 14". I said "Do you think maybe that's why you wet the bed for so long?" He laughed and said "Nah. They were just being silly teens". I asked did he tell his mom ever and he said "Nah. I didn't want to get them in trouble. They meant no harm". He doesn't.... Seem to understand the problem... Idk if I have to spell it out for him.... Or maybe should I let the topic go...

Edit: The cousins were boy and girl. They were I think first cousins to each other, second cousins to him