Regular mumsnetter here, but name changed as I don't want this connected to me via other posts 
I am separating from my husband. Still living together, but barely civil and I am trying to get everything sorted to divorce without affecting the children. There is no residency order or anything as it is early days, but I am definitely their primary carer.
My children spent yesterday, last night and today with my husband's parents. They are young, and not used to sleeping there without both parents, so it has felt like a big deal that they stayed overnight with no parent there.
The children were due to be returned this evening, but they haven't been. No contact from either the grandparents or my husband about anything all day, but when I asked when they'd be home I was told they're staying there overnight again. I don't get a choice in this apparently. My DDs are confused as they knew they were going for one night
What is the right thing to do? I don't want to go there and confront anyone as it will scare the children. But this is not ok. It is the first time they've gone, and the agreed arrangements haven't been kept to. I want them home for the rest of half term, as was arranged and planned for.
What should I do?