We have exactly the same thing in our family, and have found out that it is a genetic problem. The one thing that I now know, is that the person who is not abusive in the beginning ( the spouse of original abuser), sometimes becomes abusive to others to protect themselves. Also, they are enablers when they stay with these abusers and just stand around and watch the abuse. That was my Mom. She would get upset and cry and found a job and left us kids deal with it the best we could. It has caused a real mess. And now my Mom is basically alone with Dad again, and they are the most miserable fighting older people you can imagine!! Visiting them is entering the war zone. Sound familiar?