I can relate to your thread very well. My abuse happened around the same ages, a bit younger. My brother was 5 yrs older than me. I am female. He sexually abused me. I was taught many things to do & this was my first exposure to sex. I was clueless.
Another brother did stuff but only twice.
I can relate to the trigger idea.
Every single dam time I have male anatomy in my mouth it's a trigger. I don't think it'll ever go away.
But I have been able thru the yrs to separate myself from the abuse, know it wasn't my fault & that the human body responds naturally to certain stimuli. That can't be helped. I've learned to accept it.

I did confront my one brother about it. I'm sorry your confrontation wasn't more satisfying for you & you reached some closure.

I do also recommend counseling on this issue. There's great material out there for help.
Wish you luck English!