I definitely sympathize with you. I was sexually abused by a teacher for two years. My father suffered through panic attacks and depression. When I was a child, my alcoholic mother joked that I was crazy like my father. I WAS crazy. But I was made that way by years of being regularly raped, which my parents were too self-absorbed to see. Her cruelness is one reason why I now feel a rift with my family.
She makes jokes even now. There's no way to explain it to her. It's infuriating. You can't expect ignorant, selfish people to understand.
But you have to know yourself that there's a difference between wounded and weak. There's nothing weaker and more pathetic than hurting a child, whether with words, or abuse.
You shouldn't blame your sister though. Even if she was flattered by the attention, I'm sure she was also destroyed by the CSA.