(Newser) – Jackie Kennedy Onassis believed Lyndon B. Johnson was behind JFK's assassination, knew about her husband's affairs with his interns, and had her own fling with actor William Holden. Those are the stunning revelations from an interview she held decades ago, tapes of which are about to be released publicly, the Daily Mail reports. The tapes were made by historian Arthur Schlesinger Jr., who interviewed the former first lady within months of Kennedy's 1963 assassination. She confided to Schlesinger that she believed Johnson and a cabal of billionaire Texas tycoons orchestrated the Dallas assassination with Lee Harvey Oswald, according to the newspaper. Jackie Kennedy reportedly also revealed that she was well aware of her husband's multiple affairs, and talked of finding underwear from a 19-year-old intern working for Kennedy in their bedroom.

But she exacted revenge by having her own affairs, including one with Holden and another with Fiat founder Gianni Agnelli. Still, according to some reports, the couple had "turned the corner" and were headed toward a better relationship and had decided to have more children shortly before Kennedy was assassinated. Jackie Kennedy had asked that the tapes not be released until 50 years after her death, but daughter Caroline has decided to release them earlier; they'll be featured in a program on ABC. It's thought she agreed to release them in exchange for the network dropping its $10 million series about the family, notes the Daily Beast. (Read more Lyndon Johnson stories.)

