Welcome. My ex is classic N. Classic. However, labeling him so was never never my call. Even the mediator pinpointed him as a Narcissist, and basically said, "oh, no wonder you are having such a hard time"... but she could not "label" him officially either. Very tough. Just take the knowledge of "N' that you have and keep it in mind when you deal with him.
Stay as calm and level headed as you can under the circumstances. I know that wearing my anger on my sleeve (and he was VERY good at getting me angry....by USING my kids, of course) worked against me. The courts want to see someone who is calm, centered and only thinks of thier children, not of themselves. Focus ALWAYS on what is right for the child, even if it is good for you, too.
Calling your ex crazy (which he may well be!) and an egomaniac will only make YOU look crazy, and they don't like that. Keep the N knowledge as your secret weapon. Your other "weapon" will be your mother love.
Now, go get 'em, sparky!
Sending lots of strength and love.