CRACKS IN CAMELOT?:
Jacqueline Kennedy got back at her philandering husband by having an affair with actor William Holden, according to a new book that also says the White House couple were hooked on speed.
The tidbits are contained in "Jack and Jackie: Portrait of an American Marriage," by Christopher Andersen, published this week by William Morrow.
The book describes John F. Kennedy as having affairs with a string of beauties, including Marilyn Monroe, Audrey Hepburn, Sophia Loren, Angie Dickinson, Lee Remick and Gene Tierney and stripper Tempest Storm.
Mr. Andersen, biographer of Mick Jagger and Madonna, writes that in 1955, during the …