dp's exw is incredibly demanding when it comes to her kids coming round and staying at ours. For context, they split up in 2004 and dp and I have been together since 2018. I have 4 older kids, all adults so it's not like i haven't parented before!
every time they come and stay she complains about something. Usually it's the fact that we let the dc lie in on the weekend when she thinks we shouldn't - she thinks they should keep their school routine on the weekends otherwise it's harder to get them up on Mondays. She sends pages long whatsapps telling me what they can and can't eat because they have allergies. 2 of my dc had v severe allergies that meant we always had to carry around epipens everywhere so I am v well versed in this. She sent me a list with gluten, dairy etc. I asked dp if the kids were coeliac and he said it was the first he had heard of it. Turns out they can eat pasta and chocolate and ice cream but must be dairy and gluten free in all other foods 
and then of course, it turns out it's not actually an allergy at all, it's just a preference.
She is v organised with dates and sends them months in advance (which is fine) but then we arrange everything around those dates (and with lots of other kids and commitments, it's quite a big thing) but when she changes the dates, which she does frequently, she then sends pages of rants accusing me of being too inflexible to move things around (even when it might not be anything to do with me).
I have just been muting the conversations as they were starting to do my head in when she sent her latest diatribe which is about the behaviour of my dog and how she finds it unacceptable and it's not trained properly and behaves badly with her kids. She claims her children are amazing around animals - despite the fact they have never had a dog - and how they know everything there is to know about dogs and they tell her things about the dog that lead her to believe i have no clue what I am doing. This is despite the fact that I caught one of the kids smacking the dog on the nose when it wouldn't do what they wanted and had to take them to one side!
I have now had enough and have told dp so. She sends these messages to a group whatsapp she has set up to discuss all matters relating to the kids arrangements with me, dp and her in the group. I want to leave this group now as even muting it is not enough in my mind.
dp is desperate for there not to be a scene and says if i leave the whatsapp group it will ramp her up more and make matters worse and she will probably just text me anyway or message me directly.
WWYD?