Unsure of what to do with this information

So last night my boyfriend and I were just talking, like having deep conversations and he accidentally told me something that he has never mentioned before. We have been together for 4 years. I always knew that he lost his virginity to his babysitter but I guess I just never questioned the ages or anything. Well somehow during the conversation age was brought up and he said that he couldn’t really remember what age he was when he lost his virginity. So I just started tossing out ages like 13,15 etc. and he said no I was younger than that. He said he couldn’t remember the exact age but he believes he was around 10. So I just took that information in and it made me think well how old was the babysitter so I asked him. He said she was in her twenties. I didn’t know what to do or say. He’s never told me that before. So after a good few minutes of silence I asked him you know that’s not okay right? And his response was well I do now. I am also a victim of SA and I just don’t have any idea of what to do or feel or say about this. I tried to get him to talk more about it but he wouldn’t. He quickly changed the subject. I know I can’t force him to talk about it or anything I just really have no clue on what to do. I know that may sound dumb but I’m just having so many emotions flood through my brain. I’m hoping maybe just getting it off my chest will help some.