Jackie Kennedy's Secret Life
09/28/2011 AT 08:45 AM EDT
PEOPLE has learned intimate details about Kennedy's life through interviews with her confidants. They come on the heels of recently released tapes – seven interviews a bereaved Jackie gave historian Arthur Schlesinger Jr., four months after she was widowed.
These interviews "were hard for her to do. But she felt it was important," says her former Secret Security agent, Clint Hill.
Her friend John Perry Barlow also talks about what an accomplished flirt she was: "It was the best I'd ever seen because it was based on genuine interest."
Her feminine wiles were even used to charm diplomats to the "advantage of the American people," adds Hill, who also discusses why Jackie married Aristotle Onassis, in 1968.
For more on the newly released Kennedy tapes and her life from the people closest to her, pick up this week's issue of PEOPLE, on newsstands Friday
Reporting by LIZ McNEIL and SHARON COTLIAR