It sounds like she has a very poor boundaries when it comes to her children. It's not your fault. Everyone has a right to their personal space.

I know it seems paranoid, but you need to honor your feelings. They don't just come out of thin air. I can't remember everything that happened to me either, but I had a similar sick feeling about my father my whole life. Your dissociation is further evidence that sexual abuse occurred. I would take these issues to therapy, maybe talk to your school counselor about it. And be firm about your personal space boundaries. You're not a helpless child anymore and you don't have to put up with being touched.