For nearly a decade, I've been an assistant to a very successful man. He is an extraordinary manager and I feel very loyal to him. Last year, I accidentally found out he had a fling with a colleague at a conference overseas. Subsequently, for the first time, his wife invited me to spend Christmas with them, a sign of high esteem. It was a wonderful holiday with a large extended family and I enjoyed myself immensely. Over the course of the following year, however, my boss has continued this affair and seems obsessed with his mistress. They attend conferences all over the world and take glamorous side trips. They are constantly in touch. He is incredibly cheerful when he comes back from these events. I’ve been invited for Christmas again this year, and it breaks my heart to think of looking into the eyes of his wife and his mother-in-law, who are both warm, affectionate people. I doubt he's in an open marriage—years ago he made a joke about his wife killing him if he ever cheated on her. I feel I have been complicit by keeping silent. I am estranged from my family and don’t spend the holidays with friends, and my boss knows this. If I go, I would feel tempted to pull the wife aside and tell her, or else just burst into tears, which would be the end of my job. But if I don't go, it won't be very good for my job, either. What should I do?