He is not thinking, just reacting to his emotions. And yes, the Devil has a strong hold on him.
It’s very evident how reason, begging, pleading, logic, children, breaking of family - nothing can dissuade him. He is blind, and completely ensnared.
I 100% agree. You didn’t have an open marriage before, you don’t want one now.
I am glad the kids know. Their reaction is normal and healthy. It’s going to be a rough bit for them - be their rock and guide them. Better not bitter, compassion - that is all for you and them. It is a path that has huge dividends.
It is time to get a more formal financial protection and arrangement in place. You see how easily H justified his actions; what’s he going to do next? This will soothe him for a while, but his demons are not sated. He is driven to run.
Let your emotions settle, consider your actions, consider your reason. You’ve done loads of inner work, and have been preparing for multiple different scenarios. H finally showing his hand, gives you a direction, and as odd as it will seem, some more peace.
Look after yourself and your wonderful grown children.
DnJ
Feelings are fleeting. Be better, not bitter. Love the person, forgive the sin.