Lonecat - I have a very similar issues with my Ex. He requests changes for contact/ decides changes should happen at the last minute all the time. When I'm unable to do it, don't respond quickly enough, or offer an alternative as it doesn't fit/ can't make it work the diatribes begin!
I get all sorts of follow up contact from him - claiming I am using my son as a weapon, I am damaging their relationship, I am a jealous spiteful witch, I am a terrible mother (along with a long list of things I do that are apparently damaging our son). It's exhausting.
We had an incident at the end of last year during handover and I decided enough was enough. I told him his time with our son was to no longer involve contact between us and set up arrangements for my parents to act as intermediaries for handovers.
The nasty texts continued so I had a solicitor writing a letter, setting out the no contact at handovers and telling him contact between us was to be limited to email outside of emergencies. But of course now I end up with rafts of emails full of accusations.
He continued ot mess around with times and arrangements to the point my parents refuse to act as intermediaries so I asked ex what he wanted to do about it going forward, even provided alternative options, but he tells me I am putting barriers in the way stopping him seeing my son, and that we should return to direct handovers.
So now I have applied to court and am waiting for the first date. He is currently not seeing his son - his choice as I have offered up plenty of opportunity for him to do so.
I am hoping that having regular, routine times set out by a court, hopefully with handover arrnagements also set out, will stop all of the nonesense. There should be nothing he can argue with then, as it's all set out in black and white.
Who knows, but the situation wasn't working for me or my son with all the constant changing and aggressive spite involved.