What do you do when the other woman is your husband?

Christine Benvenuto and her husband had been married for more than twenty years and were raising their three young children in a beautiful New England town. One night in bed he turned to her and said, "I'm thinking constantly about my gender," adding that he was unhappy in his body and wanted to become a woman.

Part memoir, part voyeur's glimpse into a relationship, Sex Changes is a journey through the end of a marriage and out the other side. Christine, desperate to save her family and shelter her children, discovers...