Allow my kids to use same ID in two houses, but maintain privacy

Throughout my marriage, my ex husband has used technology to invade my privacy. He even tried hacking into my iCloud account the night I left him. Since we divorced he has continued to continually violate my privacy. He has watched my amazon purchases (I forgot I was signed in on one of his devices, he tried to tell me that the kids told him I bought them something but I had purchased it for xmas and hadn’t given it to them yet), he tracked our location using a phone he put in one of my kids bags, he used work resources to spy on me, and I suspect (but cannot prove) that he used one of my kids iPads to get into my WiFi.

I am very careful to make sure I am doing whatever I can to maintain my privacy. However, he is now asking for me to log the kids iPads into the apple account he created for them so that they can have access to the same games and such between our two homes.

While I too want my kids to be able to use this functionality, I feel like I will be giving up every piece of privacy I have. He will see their photos uploaded to iCloud and use them to make up stories about things he finds and try to accuse me of outlandish things, he will be able to track the location of their iPads to stalk us, he will be able to see their app usage and use it to accuse me of not being a good parent when in reality the boys leave their videos running on their iPads constantly. But what I am more worried about is that he will find some way to gain access through their devices to listen in to the conversations in my home.

Does Apple have any solutions for this type of scenario. Or any recommendations that can help me with this situation? Ways to set up the kids account so he doesn’t have access to the iPads at my home? Apps that we could to allow us to transfer a very limited about of data between two accounts??

This whole situation makes me so sick to my stomach and I am hoping that Apple has dealt with this type of scenario before and has a solution for people forced to shared parent with a narcissist.