Norman Mailer has been dead 2½ years, but his former mistress, Carole Mallory, and his widow, Norris Church Mailer, are still squabbling over his love life. Mallory packed Barnes & Noble on Broadway at 82nd Street the other night as she hawked her book, “Loving Mailer.” Mallory questioned the claim in Norris’ own memoir, “A Ticket to the Circus,” that Norman continued to have sex with his wife while he was trysting with his mistress. “I doubt that Norris and Norman had sex while Norman and I were together because he would not wear a condom,” Mallory said. “He once had a problem, and I had to go to my gynecologist for medicine for him. I almost called Norris to say, ‘Your husband has a dirty [bleep].’ ” Norris once explained the title to her book about life with Mailer, “Well, I bought a ticket to the circus. I don’t know why I was surprised to see elephants.”