I can't stop feeling guilty

I was SA when I was 10 years old approximately, and my cousin 13 approximately (he is 3 years older than me). My depression start at that age approximately too, so know that im thinking about it that was maybe the reason. This week i told my mom about it, im 18, so my trauma happen 8 years later, i feel guilty because she want to talk with my family, not all, but yes some people of my family about what happen, i dont want ruin his life, even if he ruin mine, if he get some consequences i will feel guilty because this happen 8 years ago. My mom dont understand why i worry so much about it, i dont understand eather. I know that maybe he was conscious about that what he do was SA, because he was 13 approximately, not 7, not 8, not 9, not even 10. He meet his girlfriend when she was 17 and he was 19, and sometimes is a asshole, but i cant stop feeling guilty about it, even when i dont understand, because no one give me sexual education at 10, and im autistic, and when i was a kid it was more dificult undertand things. Sorry for my broken english, English is not my first language, i just want know why is not my fault, because its feel like it is.