Why would you tell him?

-- perhaps hoping to hear some regret or pain in his voice? Don't bother.

-- perhaps to take care of him and comfort him? Not your job, he does not want that kind of R with you.

-- perhaps to punish him? Not productive, not good for you or the kids

There isn't an R between you and X to manage right now. He wanted a D. He wanted you out of his personal life. Respect his wishes. Leave him alone.

Best,
Oldtimer