She does have a child. Her son just turned 1 year old. He's in daycare now and she works from home. He's not in danger of being abused by his grandparents, but I get what you mean. He doesn't need to grow up around that or ever witness it.

I'll talk to my sister about seeking out a shelter and about the police. I helped her out of an abusive home situation in the past. Unfortunately, she soon went back home. And I understand that that is normal for those of us who have been abused.

I am unable to take care of my nephew right now. I'm barely able to walk due to nerve damage in my legs. I see a neurosurgeon soon. I will talk with my sister and try to help her come up with a plan. It really helps to get honest reactions to what happened. My mom and stepdad started with the gaslighting while still hitting her. They gaslit me too. "We're not abusive." You'd think that after all this time I would be better as seeing through it but it still messes with my head.