Is your DH fully aware of the list above and the impact on you?
If so why would he entertain such people? What is his motivation to see them and now to take the DC?
I think that your MH will be adversely affected in many ways - in the arrangements / when / where / how long / how often / what happens when they are there / what they eat etc .... boundaries getting set will be exhausting and then maintaining these boundaries as the PIL will just push anything and everything to exert control.
Then the mounting stress leading up to the visits.
Then the stress whilst they are there.
Then the stress of the debrief from your DH when they come back.
This will drive a wedge between you.
Then the stress of your DCs talking about the GPs over the intervening weeks - dropping random things into conversation will trigger you.
All of this will preoccupy your already stressed mind with negative shite and will drain your already compromised, finite emotional resources - don’t let this drain you - save your emotional energy for your DCs. Don’t piss it away on these people.
For what? Is it because Xmas is coming - will they want more time then - and then on birthdays - the kids, theirs, the cat’s......
If someone thumped you when you came in contact with them would your DH take your DCs to visit them? This is not much different - they have repeatedly and deeply emotionally injured you.
They have not treated you with kindness and respect - I would never entertain people who treated my DH like that and I certainly wouldn’t expose my DC to them.
What will your DC get out of this - apart from their Mums already fragile MH, deteriorating further.