In our Infidelity series thus far, we've heard from the cheaters, from those who have been cheated on, and from a psychotherapist and expert on the topic. In this final installment, the Sugars focus on the often-overlooked experience of "the other woman" and the moral responsibility that comes with the role. They discuss with the novelist and biographer Susan Cheever, who was "the other woman" in an affair...twice.