I agree with mumofmadboys, I think you’re a hero bjane to do what you’re doing for your little grandsons.
It used to be quite common for children to live with other members of the extended family & it might well be in the best interests of your GS’s for the both of them for the younger to live with your sister.
I hope you can get the professional help and advice you need to keep the family together.
You don’t say whether your GS’s are at school or kindergarten - presumably CV-19 has affected that, but perhaps things might be easier when they can return to school. I know the picture is different in different parts of the US.
Good luck & let us know how things go.
The majority of Israeli Jews do not want to occupy Gaza.
Parents-in-Law. What do/did you call them?