I am so happy to see that you are having this discussion. Yes, too many people in everyday life throw around the word narcissist for every self-centered behavior. Others refuse to discuss labels of any kind. But, there are people who very clearly meet the disorder and it is important to recognize that because you have to change the way you do things when you deal with these people.
Keep reading the articles on the narcissist's new woman and you will not need to worry that he is getting help for his happy life with her. Narcs enjoy therapy, until it gets real. Its like play-acting. IF he is going, it is because she is making him. There is nothing wrong with a narc so why would he ever go unless he had to.
Even though it is hard to admit it, yes, your kids probably would have been better off if you had lived the smaller, more stable, less eggshell crunchy life. But you can't rewrite the past and if you keep second-guessing what you did with the best of intentions for the people you love the most in this world, you will remain trapped in that place with him.
The most important part of this is that you are OUT and DONE and he has shown your children exactly who he is and what he is all about and it ain't them. You have a life to live. A glorious one. Full of love, laughter, and family. Three things your X will never truly have in his own life.