EARLY one morning, 50 years ago today, while his wife, Mary, slept upstairs, Ernest Hemingway went into the vestibule of his Ketchum, Idaho, house, selected his favorite shotgun from the rack, inserted shells into its chambers and ended his life. There were many differing explanations at the time: that he had terminal cancer or money problems, that it was an accident, that he’d quarreled with Mary. None were true. As his friends knew, he’d been suffering from depression and paranoia for the last year of his life. Ernest and I were friends for 14 years. I dramatized many of his...