When we reach a point of realizing that they are adults and all of our 'help' is only keeping them in the same spot in life, we change. Our difficult child's are hardheaded and mine doesn't appear to learn from his mistakes, but that is his life and I have mine.
I know some of my close family members disagree with me BUT, in my opinion, they are adults, our job as a mother has shifted and changed definition. We are not talking about children, they are adults.
I had the same situation with my difficult child's long lost father. It's as if they think we are totally responsible for the kids. I told him we were divorced and the relationship between him and difficult child was what ever they wanted. I refuse to be the 'go between', if he wants to know what's what ask difficult child.
Detachment does not mean we love our difficult child's any less, it means we love them enough to let them learn to be a responsible adult.
Huggs and Peace!