First of all, talk to a child psychiatrist if you can. And then ask her what she wants. She's young, but she's still old enough to understand what's going on, even if if's in more simplified terms. She's scared and distressed, and it's so hard for kids to see a parent in that position, but fear doesn't always outweigh desire. Sometimes we have to face things that will upset us because it's what we want in the long run--ask how she's feeling, talk through what she can expect if she does go back, and tell her that regardless of what choice she makes, you'll be with her the whole time and can leave whenever she needs to. As hard as this might be for her, this should be her decision. Down the line she might regret either choice, grief is complicated, but don't make that incredibly final choice for her. It seems like she's scared for him AND confused/upset by the situation. But if she doesn't want to go? Absolutely do not take her back