We have a family agreement that we don't promote contact between our kids and any person who is disrespectful to any one of the four parents. She was badmouthing me every time they were together. Thus-the kids weren't free to join. She wanted the youngest child to come and entertain her child so she could have more freedom to be with dh unhindered by her childs demands for attention.
When her pressure for that got significant-he started pressing me to talk to her and "resolve" the issues.
So I let her know that her derogatory comments bothered me. That pissed her off because she felt it was "private" and any derogatory comments she made were none of my business unless spoken directly to me.
"Love As Thou Wilt"