I’ve experienced what you describe, but I’m not sure about if I would call what I suffered “severe abuse”, or what you consider that to be.

1. If it’s not “severe abuse”, You try to have empathy and forgive that person. Humans are very flawed. (I’m considering “severe abuse” to be rape, murder, and similar...actually I had a date rape and aren’t even mad.)

2. They will get punished somewhere down the road. Karma’s a B. You don’t have to do anything, they will get theirs as they have it coming.