MHL, Thanks for sharing on this post. I am terrified that my D8 and S6 have your kids' experiences in their future.
My W is a product of marital problems between her folks. She has been in two failed marriages. She doesn't understand that the pain she felt as a child has led to extreme control issues which lead to begrudging compromise and blame for those around her when things blow up.
Most distressing is that she fails to see the pain she felt as a kid is being inflicted on our D at the same age by her choices. She has kept contact with the kids, but the cycle continues and I have no control over it. My W has spent the last two years looking for validation that she is a "good Mom".
However, your responses to your XW's actions are admirable and provide a road map for me to attempt to emulate.
The only thing I can offer is to be good to yourself. Sustained periods of high stress, being SuperDad have a devastating effect on your health. Your kids need you, but you need your strength. Find some time for breather. I struggled when I realized I was translating my anger and upset into impatience with my kids. Decompress.