Joan Didion’s 2005 bestseller, The Year of Magical Thinking, left her readers a bit shaken. The rending account of her husband’s death was cast in a demimonde of disturbing shadows. For quite a time it tossed her into a twilight existence of strange disconnections and fantasy expectations. Hence her tantalizing title. Her mourning bore no resemblance to reality, only a loose pastiche of semi-mad…