Silverma
My son really needs my help with childcare while he is working. DIL does little with the children. In a way, my son is, without intention, is putting pressure on me to do as she demands to keep peace in the short term whilst he thinks about how to deal with this. He has to be careful as he is worried sick that he will lose the children. So basically we are all in her hands.
With respect , your son (and you and DH) are allowing her to succeed in making you all behave like people guilty of child abuse.
She's making you keep quiet, when you should be doing the exact opposite. INFORM social services and police that she is using false accusations to coerce you.
If you don't get a grip on this, GS will pay the price. As soon as GS becomes old enough to challenge her or assert himself in normal childish ways, she will use coercive means tocontrol him. Children subjected to coercive abuse by their parent, face lifetime psychological consequences.