It would have to be quite a sacrifice for you, Z_Bube, to live in this M and know that she is not likely to change. That is a personal choice you will have to make. She will definitely have a negative affect on the children so you staying until out of the house makes sense for their sake.
My aunt was diagnosed with narcissistic personality disorder too and she no longer has any contact with her grown children (by their choice). My mom (her sister) talk sometimes but only once or twice a year to make sure she is doing ok. It is so hard for a narcissist to hold any sort of healthy R's. I feel for you Z-Bube.