Sorry it's been a long time since I caught up on your thread, I just needed a break from it all.
I don't think we will ever understand how they can turn away from us and spend their time with OW and her children! I cannot imagine spending more time with another person's children than my own! They must block it all out in some way to be able to deal with it.
It is hard to know whether to try to include them in things like egg huts isn't it? I have started to just casually mention things I have planned - like a hook on a fishing line - and see if H takes the bait. Most of the time he doesn't but I've decided it's his loss not ours.
Stay strong, this is the hardest road to travel and you're doing so well.