Communication with a narcissist can be nearly impossible and is exhausting and anxiety inducing.
There is a term, Gray Rock, which is the fastest way to heal after a relationship with a narcissist. It's being as boring and as uninteresting as a gray rock. By doing so, the narcissist in your life will lose interest, because you're not giving them the supply they so desperately need. You aren't adding fuel to their fire, you're in fact extinguishing their flame with your boringness.
I wish everyone could go no contact and gray rock.
Sadly, for so many of you, you are forced to continue to engage on some level, because of your children. You are forced to communicate, so you can't gray rock, but you can adapt gray rock to yellow rock.
It's just a nicer version of gray rock.
You'll always keep your communication to writing and keep it (BIFF):
brief
Informative
friendly
firm
You'll never ever (JADE):
Justify
Argue
Defend your position
Explain yourself
You'll keep it succinct and unemotional. Remember: any and all emotions are fuel for them. They get off on your anger and frustration and will use you happiness to hurt you.
Keep it business.
And to follow in the yellow rock communication vein, you'll add in niceties. Things like, thanks, I look forward to hearing from you by...., and please.
Remember: you're not only writing to get in and out as quickly as possible and stop the circular conversations that drain your life force out of you, but, you're also always writing as if it were to be read by a judge. A judge that doesn't know which of you is the instigator, the antagonist, the high conflict party in what they deem a two party conflict.
My rule of thumb is this: if you wouldn't feel comfortable reading your text/email out loud in front of a huge, do not press send.