I agree on the use as little words as possible when dealing with a narcissist. You can't debate them or resolve anything with them, so don't waste your words on them. It's pointless.
I recently received a message from my abusive, narcissistic brother-in-law who didn't like something I said on social media, but elaborated it with what a terrible person I was, and how he was wonderful, and my response to his long blowhard message was "ditto." He never answered me back.