Book details teenage intern's White House affair with JFK

President John F. Kennedy, seen here in a file photo, had an 18-month affair with her, author Mimi Alford claims.

(CBS) "Once Upon a Secret," a steamy memoir detailing Mimi Alford's 18-month affair with President John F. Kennedy, hits store shelves on Wednesday.

Photos: JFK's White House Years
Photos: Jacqueline Kennedy Onassis
Photos: JFK's Early Years

In the book, subtitled "My Affair With President John F. Kennedy and Its Aftermath," Alford claims she was a virgin when she started the affair as a 19-year-old White House intern. She last saw the president the week before he was assassinated in Dallas on Nov. 22, 1963.

According to excepts published in the New York Post, the now 68-year-old grandmother described how the 45-year-old president, whom she met in the White House swimming pool, took her virginity in Jackie Kennedy's bedroom.

Alford, who was Mimi Beardsley when the affair took place, has said she wrote the memoir to give her side of the story after she was romantically linked with the assassinated president in several presidential biographies.

Kennedy's womanizing has long been a matter for biographers, though it was little known to the public at the time.

"Once Upon a Secret" is being published by Random House.