I told my parents about my CSA when I was 25. I was abused by my eldest brother.
I won't lie- I wish sometimes I'd never mentioned it. My dad had a difficult relationship with my brother anyway, due to brother's violence, and ultimately severed all ties with my brother, even to the extent of disinheriting him. (For clarity- my parents have been divorced for 40 years).
My mother, though, while claiming to be upset/horrified, has only ever used it to demonstrate how she felt about it. And has consistently, over the 25 or so years since I told her, told me how she knows brother is 'sorry', and she knows he's trying to change his ways (he's nearly 60 ffs), and telling me how terrified she is when he visits her (yet never refusing his visits).
I stopped contact with her a few years ago, but recently agreed to have contact on the strict proviso that she never mention it again. Unfortunately she chose to bring it up in a café, and the anger came rushing back and I told her that if she ever mentioned it again I would leave and she would never hear from or see me again.
However- I am relieved that I told them, as I also told my siblings. It transpired that eldest brother had also abused another of my brothers, who had kept it to himself as he believed he was the only one. Painful though it has been to know that he went through it too, it has also given us both some relief to be able to talk about it.
Only you can know what your parents are like- whether they're likely to be supportive or not. I agree that it's definitely worth talking to someone else about it first- whether that's a counsellor or a friend- just in case you need that extra support to deal with potential family fallout.