Interesting posts. My mother in law was the most difficult person I have ever had to deal with. For the last 10 years of her life I had to emotionally shut her out of my life. I don’t know how to classify her.
These are very toxic and manipulative individuals who divide to conquer. The advice I have had from professionals is to walk away. You cannot do a thing to change them and if you attempt to interfere in the family dynamic they engineer, you play into their game.In my family, even the grandchildren eventually had to just walk away.
Your wife and children are probably the ones who need the healing. It is easier for the in-laws.