How old are your kids? Why would you need to text him pics of them?
I would think part of detaching and going dark would mean keeping him informed of important kids' events (school things, ball games, dance recitals, etc. if they're involved in that), and not blocking access to kids if he wants to see them, but also not texting him pics of them for no reason or just because he wants them.
Maybe a good boundary could be something like: You're welcome to set up times to come pick up the kids and do things with them if you want to see them, but texting pics is not really necessary.
