OP, I have read all of your posts and a few of the others.
The main thing which leaps out at me is how nice and decent you think he is, and how un-decent and un-nice he really is. I wonder how long he has been deceiving you, or if he's really had a recent personality change, or what. His attitude towards you is unforgiveable, unkind and beyond contempt. His lack of compassion, remorse for the hurt he's caused you, and will cause his children. His attitude of calling the shots instead of asking what is best for you, and how he could help you. The way he spoke to your brother after what he's done
. All these are on top of the adultery, and in my opinion, are even worse than shagging someone from work as they don't just reveal a weakness but a deep personality problem. I know you may not be ready to hear this, but I think you and your children are better off without him in the long run. You may start seeing things about him which have been there for a while, the old MN 'red flags'.
I had an affair when I was at work, and was very young and ridiculous. I know how people can get into these things. I think I could forgive it. I couldn't forgive how your H has treated you though. The guy I had the affair with did end up leaving his wife, but he was pretty broken and his attitude was totally different to your H's here - not to condone his behaviour and I am extremely glad I never married him, but just to show it is possible to do some pretty awful things and still be sorry, and communicate the remorse.
There are levels and levels of deceit, control and a total lack of concern for anyone else, or any remorse, which shock me quite deeply. Checking out of the marriage a while ago is no excuse whatsoever and his ability to detach is actually very, very scary.