The inability to let it go, the irrational guilt, the self-anger: I knew these signs. Wrong thinking. There are methods to stop it, psychologists say. And mental health requires that it be stopped. For the writer, a dilemma. For the writer, obsessive rumination is a must. Imagination must follow dark thoughts to dark places, you can’t ever just say, Stop, don’t go there. And isn’t that the job, to imagine the lives of others and what they are going through?