I can tell when I've really pushed the envelope of my own boundaries as far as what I'm willing to do to a character. I will actually have a hard time facing up to it, for some weeks. I might find myself shying away from writing details. And what I do write is generally the character going through grief reactions: shame, anger, self-pity, etc.
Eventually I will realize I have worked it out, and then I have to go back in and add strength to the character. Nobody wants to read a bunch of crying, lashing out, pity and horror without at least a good dollop of fortitude. But sometimes I need time to find that fortitude myself.
It's a good illustration, to me, of how stories help us to learn how to cope with being human.