does a person ever really get over a decades-long brain-screwing by an authoritative, oppressive, soul-sucking - [parent]
Why, yes. Some adult children somehow manage to rise above their past. I don't know why some rebound and others self-destruct, but I suspect it has something to do with inner will, choices, and the chance to see what good looks like here and there. One fine adult who came from an abusive home told me she got her inspiration from teachers and librarians.
Adult children who recover from abusive pasts also have a few things going for them. They recognize and reject manipulation and abuse. They can be more sensitive and caring parents.
After all, we all are the sum of all our experiences. Even the bad memories can serve as an example and a warning as we wind our way thorugh life.