1. Well, ditching your old friends/pets/children/spouse is a typical trait of MLC and they usually get replaced by younger and/or like minded single/divorced people who will support your H's new life/lifestyle/romantic interests. Typically, looking younger (working out, dying your hair, plastic surgery), acting younger, and fears of aging/death are also part of the package. Also, going back to/getting stuck on some prior trauma from youth/family of origin is also part of the package (conscious or unconscious).
2. Re your H's reaction to the counseling, I think the advice given to me which I will pass on to you is to keep your expectations at ZERO. This is for your protection. When you expect him to do the normal thing (show concern for his children) and he doesn't do it, it only upsets YOU. Treat him like a male neighbor or a store clerk. You can be polite and friendly and ask them about their day or the weather, but you don't expect anything from them emotionally or physically.
3. Yes, that's the book. It's literature, not self help, but can give you insight into the walk away husband's mindset and the crazy things he can do. Not sure you want to read it in your current state of mind/situation, as it may hit too close to home. But it's a classic of 20th century English language literature for a reason, so thought you may have bumped into it along the way. Maybe read a summary of the book before you buy it and decide whether or not it is helpful/hurtful for you.
Gordie 40s W 40s M20+ kids 2016 BD W fantasy affair w OM1 I do everything wrong 2017 I start to DB W says TLTL files for D PA w OM2 2018 I do LRT W drops filing and OM2 situation slowly improving