I have 11 yrs. D from my kids mom and she still will pick a nerve and feed on it at times.
One big key to my own mental well being and of course that of my kids is I have learned to ignore the petty BS that can't be won or addressed rationally with her.
A most recent example was a snide comment about spending time with S14 and me being a bad dad. I hung up on her instead of engaging. Without the confrontation that comment was rendered moot.
I could list years of examples and ways I handled them both good and bad, but the main theme is we aren't going to change "their" bad behavior!
In my experience deflecting your childrens questions or comments concerning their father when it appears they're seeking a judgement or affirmation from you works best at not antagonizing.
Children will come to their own conclusions over time so there is no need to bad mouth or even push for their father to act as a "good" dad (as is your perception).
Pick and choose only those battles that really matter, it won't fix everything but it will help with the ulcer!
As far as wishing he would have just left and not looked back, it would have just created new questions and problems. With him here you will be vindicated in your childrens eyes one day because it seems that leopard can't change his spots!
Thoughts and prayers
cire
Me 48 X's vary S 27 S 18 Back with high school sweety after 30 years..