Agree..
I also thought, you did the right thing getting him to face his DD and explain it himself. He's a stinking coward and he hoped to use you as the messanger for all the unpleasant facts to convey to the children - so he didn't have to
Also. How are you expected to understand his last minute mind change and convey that to the children. He's so spiteful and pathetic.
But also because he's such a nasty lying piece of work, so that he could claim complete innocence to the children and falsely accuse you of the entire break up.. "Well Mummy wanted me to leave so I had to kids, I'm the good guy, she's the bad person." More difficult for him to welsh out face to face and at the time, rather than a year down the line. They will remember. Let this be the last time you have to be his messenger.
Totally agree, no more discussions with him. He's not going to reasonably discuss anything, he just uses it as an opportunity to hurt, insult and falsely accuse you. Record in the parenting app that since he refused on xx date to discuss access to DC.. your suggestion is as you've said before xyz...let him start accusing you by text if he's going to and then you have a record of what a swine he's being about this.
Your children will be OK - because they have YOU, clearly a far better person to be in charge of them.
A hard weekend for you, but the thorn in your side is about to remove itself and then the only way is up. 