Roger Ailes did more to degrade the tone of public life in America than anyone since Joseph McCarthy. In 1998, Ailes asked me to drop by his office in New York City. The Monica Lewinsky scandal was exploding, and Fox News’s prime-time ratings were soaring because of it. I had gone public in defense of Clinton’s insistence that he “didn’t have sex with that woman” — saying I doubted he’d jeopardize his presidency for an affair with a White House intern. But privately I also knew about allegations of extramarital affairs stretching back years. During Clinton’s 1992 campaign, one of his trusted s…