I once had the MIL from hell SHe hated the very thought of me. She treated me rudly and ignored me when ever there were family functions. She always had negative things to say about my boys. She was such an old bat and had so much hatred in her heart. I did not let that stop me from sitting her down and in a very stern way, telling her I did not appreciate the way she treated me, and my children, and from now on, she's not invited to come over! I wanted no part of being mistreated in my own home.
She actually calmed down. Eventually they were invited over. Eventually all of it calmed down.
It's like they refuse to let go of what is no longer theirs.