Someone with a ''golden heart'' would not be abusive or hurt a child. Having depression is no excuse for abusing other people. Worse, you say your child is even scared of her because she hurts the child?! That is all you need to know to inform as to your next course of action.

I would not let this woman hurt a child. What to do? Protect the child. If that woman will not seek help and is abusive, then protect the child from further abuse.