Well, when applied properly, that term describes pernicious pervasive patterns that are different in very important waysthat can be accounted for by "people do crappy things".

And in fact if that term IS being properly applied (and I suspect it does based on a few things and my experience with this diagnosis) then the details actually did NOT matter in the way we normally think of.

OP, I can tell this is the straw that broke the camels back. However, let me assure you that knowledge is power. If you are truly versed in the patterns of a narcissist, you will find that you have powers over them that you would never consider taking because you are in fact a normal person with normal expectations. But here goes: Narcissists do not understand dealbreakers. YOu know this, it seems. The negative for you is that you cannot ever get the satisfaction of acknowledgement by the narcissist of wrongdoing. The PLUS is, you can literally completely ignore the topic and it will not come up again. Why this is a plus: you dont need to take te responsibility of addressing it. Instead, you have all the info you need, and now she never gets to be with your kids alone ever again. But rather than making a grand statemetn about it, you just make it so. She does not need an announcement. Just make it so that they are never alone again. THAT is both your strategy and your satisfaction.

Its not a normal way of dealing with problems and conflicts, but its the ONLY way if you have a narcissist in the family.

MY dad married one after my mother passed, and let me assure you, its been QUITE the education. But once I understood what I was dealing with _exactly_, my life became much easier. I also had to let my father go, for his sake, as I knew she punished him severely every time I pointed out to him what she was doing. (I never used the term narcissist. And dont you ever let her know you have this term for her, because you are buying yourself a world of pointless grief if you do).

As a result, my father and I now finally have a relationship again. I am completely OFF THE RADAR of the narcissist. THAT is how you move forward. You just set the limits and feel free to make excuses each time. Master the "easy breezy". its your go-to survival tool. All conversations are to be kept superficial. YOu will save yourself so much time and grief if you follow this advice. Please please please. I went through years of pain to arrive at this knowledge. I hope to spare you the same.

So, place the kids in ANY activity while the N is around and never give her unattended access. And just go onto the internet every night after the N is sleeping and verse yourself in what pathological narcissism is. The stories you read will make your blood run cold, but I swear, you will find stength and wisdom in the experiences of others.

Ignore the topic, know that you know everything you need to know about her and what she did, which was not just careless and stupid BUT highly arrogant in the way only a narcissist can be. You already know what you need to know. There is NOTHING MORE TO KNOW.

Just be easy breezy and she will TOTALLY RESPOND IN KIND. That is their nature.

Your husband is aware, and he has had to live with it his whole upbringing, I imagine. So he knows all about the easy breezy and deflecting confrontation. REMEMBER: You are NOT avoiding confrontation to help the Narcissist. You do that to SAVE YOU AGONY AND POINTLESS STRUGGLE. So, as you do the easy breezy, remember you are doing this for YOU and not HER.

Good Luck OP. You will do this fine.