DUSTY Springfield hid her lesbianism for years, claiming men were too spooked by her success to wed, a new book about the “Son of a Preacher Man” singer reveals. In “Dusty! Queen of the Postmods,” out in November, “Catholicism was recruited to explain her reluctance to marry the rare man who might have been undaunted by her celebrity,” writes Annie Randall. “Dusty [said], ‘You have to concentrate on marriage and I’m a Catholic and can’t get divorced. I’m so self-centered.’ ” Springfield, who died in 1999, loosened up later in life, telling one journo: “Am I gay? . . . If you want to know the truth, ask the people who go to bed with me.”