I don't see how you can hide it from the kids anymore. You may not have to tell them he has a girlfriend, but you can explain to them that he wants a divorce and you won't be able to be their mother under those circumstances. So someone has to take some responsibility in that house. You tried it for the weekend to see what would happen, and it was a dismal failure. So now what? As nice as you are, this isn't your problem. It's theirs.
He'll say he isn't planning to divorce you for 2 more years. He will just make you miserable for that time and treat you like a servant. But you don't want to be his servant. So his plan isn't going to work. The family needs a new plan.
