Scott, in the future try to arrive after her so you can sit by yourself. Nobody needs that kind of stress. I probably would have been pretty direct with her. When she started talking about the argument with the friend, I probably would have stopped her and said: "What, are we girlfriends here?" (I love that line by Denis Leary from The Ref!)
Now that the divorce is final, and everything is settled, I would let it be known that I am not interested in discussions outside of coparenting. And I would bring up the support next time she complains about buying clothes for the kids.
Love this update. You are knocking it out of the park, Scott!
M(53), W(54),D(19) M-23, T-25 Bomb Drop - Dec.23, 2017 Ring and Piecing since March 2018
