Remember how your narcissist made everyone think that he had a wonderful, stable life with YOU? And how eventually it became all your fault? Remember how in the beginning you were so infatuated with him because you believed everything he said, which made him put you on a pedestal?
Narcissists don't seem to learn from experience, and is even now at this moment little by little losing interest in his brand new object of narcisistic supply, as she is most likely realizing that she will never come first, in everything from who gets the remote to who does the dishes to major life decisions, and that there is not much of value in his shell of a person, especially when there is no "audience" to perform to.
Possibly the only time they are really clicking is in public, which is how rumours of a wonderful stable life are getting back to you.
Please do not let any more of this control you! You won already by getting out!
Pray for this new woman to have the strength to not lose herself into his life, and give yourself a hug for being such a brave person to lead in her own life!