No one is under any obligation to be the exact same person they would have been had they grown up in a safe fluffy world where nothing bad ever happened to them. Our experiences shape us as people. Personally, I don’t believe that rape can change a person’s sexual orientation; however, even if your asexuality is linked in some way to your rape, that doesn’t make it any less valid. It’s still a part of you, and you get to decide what to do with that. How to feel about it. How to react to it. It’s yours, all yours, regardless of where it came from.
I hope that helped, anon, or at least that it didn’t make things worse. I’m really, truly sorry for what happened to you. *insert emotionally comforting gesture of choice here*