Hmmmmmm
He has hardly seen them since being back whilst you were still at home, has threatened police/SS, checked labels, not provided any extra money etc and now he is asking demanding to see them. 
I can defo understand your thinking Mo but can also understand what grumpy is saying.
If you decide to let him see them, let him come to you and don't go to the house.
This way, maybe your relative can facilitate it making him feel very awkward, and you can control how long the contact will be.