I've no advice, Liisi, but I know how you feel.
The first time Gerbilmommy went away with a friend's family (she was about 8), for a long weekend, I couldn't relax at all. They went to their house near the beach, and I was worried she'd get into difficulty 'swimming' in the sea. Or what if the house went on fire, and they had no fire alarm? Or she got run over, trying to cross the road. Or the driver of the car was speeding?
I'd no contact with Gerbilmommy for 4 days, and felt like part of me was missing.
She was fine, though.
But I've had times when I had a couple of near misses in the car - not through speeding, just bad driving or other vehicles being stupid.
When you're not there yourself, it's easy to imagine what could happen. It's difficult the first time, but easier as time goes on.
Your ex is probably unlikely to let the children be in any sort of dangerous situation.
They may end up wearing the wrong clothes, or eating food you might not approve of, but those things aren't the end of the world. Hopefully he'll learn as he goes along, and appreciate all you've done for them, and him, over the years. It's good that the other relatives will be there, to help the situation along. Hopefully your children will knock the corners off their Dad - and he'll realise that he can't have perfection, when it comes to dealing with small children.
At least you can phone - that will put your mind at ease.
