Poor Katie Couric. Already fending off sagging ratings and an out-of-the-blue bitch slap from the New York Times, America’s most overpaid anchor, sources say, is quaking in her Christian Louboutins about an upcoming tell-all that an ex-boyfriend is writing for Gotham Books. The perennially perky Today host, who had a tempestuous affair with Park Avenue plastic surgeon Cap Lesesne, is apparently worried that the famously indiscreet doc intends to share secrets about their relationship that she’d rather keep private. (The title of his book, Confessions of a Park Avenue Plastic Surgeon, may have been the tip-off.) But from what we’ve heard, Couric doesn’t have too much to fear, particularly among the coveted 18-to 24-year-old male demographic. Though Lesesne, whose clients reportedly have included Hillary Clinton and Barbra Streisand, was recently heard telling friends that the kittenish TV personality is a wildcat in bed, he went on to add that he hasn’t decided yet how much, if anything, his book will reveal about Couric. If the tome proceeds as planned, we’ll all find out October 6. Couric's publicist, Lauren Kapp, declined to comment.