Need advice for a WW who left Part 2

[dwh15]

Only 2 of the kids went to see mom last night. Same 2 as always: S18 and S8. Other 2 with me, as usual. WW took them bowling and out to dinner. They had fun and S8 really wanted to spend the night but WW had plans to go with OM to a late night dinner (midnight). She wanted S8 to come along, but he was way too tired, and decided to come home. I don't blame him. Who in their right mind thinks that an 8 year old wants to go to dinner at midnight?

But after he got home, I could tell he was upset. He had really looked forward to staying, and mentioned he missed mom. I did my best to comfort him and eventually cheered him up a little. But it's the kind of thing that tears my heart out. I just don't understand how a mother can abandon her children like this and barely spend any time with them for months on end.

It bothered me enough that I texted WW and told her S8 seemed upset, like he had really wanted to spend the night. She replies back, almost defensive, that she had tried to convince him, but that he was always torn, would think I would miss him and be upset with him. Or that he would miss something fun I had planned the next day. She still seems bitter that I'm trying to plan fun activities with the kids, like it's all a plot to have them like me more than her. She never considered that maybe S8 simply didn't want to go to a midnight dinner with OM. Why is she making plans like that on days she is supposed to have kids anyway? It's extremely frustrating. I can only guess that it's part of a wayward mentality and hope that she eventually comes out of the fog. She is permanently damaging her R with all her kids.