Beloved Mets catcher Mike Piazza comes out swinging in a new memoir — confronting rumors about being gay and taking steroids, detailing his romantic home runs and finally settling the score with his hated rival, Roger Clemens.

The book, “Long Shot” (Simon & Schuster) comes a month after Piazza, arguably the greatest hitting catcher of all time, fell 98 votes short of being voted into the Hall of Fame in his first year of eligibility. Many think he missed because of persistent rumors he used performance-enhancing drugs during a 16-year career.

The 44-year-old makes no bones about holding a grudge against Clemens for beaning him during a July 8, 2000, game, and for the infamous bat-throwing incident later that season against the Yankees during the World Series.

The 98-mph fastball to his helmet could have been deadly.

“I truly believe that if I hadn’t gotten my head down at the last instant, Clemens’ two-seamer would have struck me in the eye and possibly killed me,” he recalls.

The Yankees hurler called the Mets dugout to apologize during the game, but Piazza wasn’t hearing it.

“I grabbed [the phone], threw it and said, ‘Tell him to go f--k himself,’ ” Piazza said.