Help please

When I was 5 my brother started messing around with my sexually. I never really thought anything of it or that it wasn’t normal. My parents would catch us (twice I think) and we would get in trouble, but I never understood why. I consented to this happing until I was 13, when I got my first boyfriend and I realized you’re not supposed to do these things with a family member.

I’m very confused on what to call it because it was consensual but I feel so weird about it. It shouldn’t be a thing that happened. I shouldn’t of become sexually active at the age of 5.