I'm so sorry about all of this. It sounds like you've made a decision about your treatment and I do understand that you want to be here w/your children and I can't blame you for that.
Now about your husband. He's not happy w/his life. He's not happy that his older children aren't jumping on the band wagon and cheering him on w/what he's done to their mother and family. He has to blame someone for what they are feeling...but he's doesn't want to look at himself and his behavior as to why they feel the way they do. They are practically grown adults and have feelings and yes, a brain to think things through and have their own thoughts on things.
Demanding and controlling are the two things that NPD personalities exhibit towards their victims. Give him the grades each and every month and hopefully that will stop the nonsense about those...but I will warn you, he'll come up w/something else to demand that you "jump" when he commands. It's a control issue and he still wants to control you and your children every inch of the way.
Please take care of yourself. I am very worried about his attitude towards you.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.