We'll agree he is a loon, as long as you promise not to get drawn into his stuff. Do Not respond to any statements regarding his being arrested without proof, or his men's group, or anything not directly related to the kids. He will imagine your responses to be what he thinks and wants instead of what you said.
In fact, I would suggest letting him say whatever makes him feel normal, as it may improve his behavior. But don't go so far as trying to validate anything other than pickup times and locations for the kids. Validating his meaningless attempts to portray himself as perfect guy will only lead him sense some kind of victory and control. You've seen that lead to him wanting more of both. Try to keep your posts shorter than his.
Think of it like testimony in court. The more you say, the more doors you open to cross examination. The more doors you open to being taken out of context. Not saying be rude. You know how to be polite or say thank you; just do so in brief exchanges.
No need to challenge his opinions of the kid's living arrangements at your home. They are what they are and they are not up to him to judge. He does not get to vote. Whatever he says the kids are telling him has no weight on how you raise them right. Unless he alleges something criminal or harmful to their health is going on, you need not respond to LooneyTunes dialogue.
Focus on the high road and avoid meaningless distractions. Take care.
