My W tries to send me funny texts and jokes and stuff. I don't respond AT ALL. I only respond if she asks, "What time do I pick up the kids?" or "Do you have S7's lunchbox?"
Even then, I respond with yes, no, or OK.
It's been a long time, so I'll be a little pointed, and hope you'll forgive me - but do you get some sort of rise out of this? You continue to talk and talk and talk about what he says to you - why do you even respond?
What possible purpose would you have for any involvement whatsoever in his life?