Calvin Klein, whose 22-year-old ex, Nick Gruber, is penning a tell-all about his relationship with the designer, won’t be writing his own memoir. “I have no interest,” he told us during a Peggy Siegal party for Penny Marshall’s book “My Mother Was Nuts” at Monkey Bar on Wednesday. “I’ve spent most of my adult life speaking to press and trying to communicate what I am creating, and so much has been written. Because it’s so personal . . . and so much has been written about me, I’m sick of hearing it, to tell you the truth.” He continued, “I don’t need to tell the story myself, it’s been told.” Of Gruber, who is currently dating John Luciano, Klein tells us (possibly through gritted teeth), “I’m very happy that he is happy.”