In the last chapter called "Confession" who is speaking and is the speech ironic? Why does the author end the book this way? What does the confession imply about our ability to separate out the "enemy" in our midst?

The father is speaking in the last chapter. The author ends the book this way because although we meet the mother and hear her perspective at the beginning of the novel, it is the children's perspective throughout the rest of the novel. Allowing the father to speak in the end allows to hear all points of view.