There was a well known poster who used to like to haunt these halls to tell everyone that they should just leave/divorce rather than expect their DP/DH to make any sort of adjustments for the fact that he was no longer with his childrens mum.
Upset that your husbands ex has a key to your home?
"This is your elective choice to be with him, if you don't like their co-parenting arrangement, leave."
Feel disrespected because whenever you have child free plans, ex snaps her fingers and your landed with the kids again, plans scuppered?
"This is your elective choice to be with him, if you don't like their co-parenting arrangement, leave."
He agreed years ago to pay for XYZ for the kids, but now your Household can no longer sustain it so he wants you to use your personal savings?
"This is your elective choice to be with him, if you don't like their co-parenting arrangement, leave."
At no point should the man behave with any kind of loyalty towards his actual wife or even his younger children.