greencar it sounds like you can't do anything to change the situation today. As you say, just hope he comes back when he's said he will.
What I'm about to say might sound childish and irresponsible. What if you were to turn the tables on him from now on? Not to the detriment of the dc, but be as vague as him. Sod it, if he says he's coming at x, you say no it has to be y, then you go out and come back at the time you said. If he's waiting outside at "his" time, good.
What is actually the worst that can happen? Apologies for not being able to remember the details of your contact, eg court ordered, but within the confines of your agreement what is the worst case scenario? He'll tell his "friends and family" how awful you are - well he does that already. He'll say bad things to the kids. I guess he also does that already. I bet they already sense how he mucks you around. Really, if you behave like him, what can he actually DO - not say, imply, threaten - but put into action?
Lilac don't beat yourself up with hindsight. All your trust will have come from a good place. He's the liar. His life is the tissue of lies, he knew it then and he knows it now with hindsight. Your hindsight exposes only his failings and your strength of character to try and keep your relationship and family together.
Frog I'm envious of your roast, that would be an entry in the Great British Bake Off final in my house at the moment! Am trying to resist the temptation to eat the Halloween trick or treat sweets at the moment. Made a couple of raids last night (I'll blame the munchies). Will have to empty everything into one bag before the dc get back or else they'll rumble me !!