The tragedy would be that he is still the good man who has already subconsciously done so much that he would identify as evil that he now feels he has nothing left, it isn't worth trying to fight it and starts justifying it.
The subconscious demon becomes his waking self.
It's impossible to feel sympathy for someone who consciously murders children.
Someone who does it and doesn't know he's doing it until it's too late is far more tragic.