The New York Post said the book by Edward Klein, entitled "The Kennedy Curse," includes charges that Carolyn Bessette Kennedy admitted to her husband she was cheating on him, abused cocaine and often engaged in violent temper tantrums.
An authorized Kennedy author, Laurence Leamer, told the newspaper both the Kennedy and Bessette families are extremely upset by the revelations.
The couple died, along with Bessette's sister Lauren, when the small plane John Kennedy was piloting crashed into the Atlantic off Martha's Vineyard on July 16, 1999.
Klein writes the planned daylight flight had been delayed until dusk because Carolyn insisted upon having an overlong pedicure before going to the airport. That, the New York Daily News said, resulted in Kennedy flying virtually blind into the hazy dusk, which investigators blamed for the crash.