I learned that if I tried to stand my ground (with my mother) I would be beaten to death. Well, I felt as though that would happen. It does happen in reality sometimes. Read about it in the news frequently.
And the worst part is that no one will intervene. They all seem too afraid. The sense of not being able to fight, not being able to flee (my mother would punish any such attempt), leads to the overwhelming need to dissociate -- to just "go away" mentally -- not be there. It was the only way I could find to survive. Hence the mental disintegration that still persists in me today at times. And which many people, including mental health people, think is just some way you have of tricking them...
My mother could not handle any kind of opposition -- or even difference. It was a challenge to her that had to be beaten back, by any methods at all. Characteristic of people who feel their very sanity is threatened. I see some political leaders with similar tendencies -- I can think of a couple offhand -- foreign ones, that is...
That is why I think the word "borderline" is justified -- they feel on the edge of disintegration, all the time.