While more and more has come out about JFK’s extramarital affairs in the years following his 1963 assassination, what’s always remained a mystery is how much his wife, Jackie Kennedy, really knew.

In a new book, Jackie, Janet and Lee — excerpted in this week’s issue of People, on newsstands Friday — author J. Randy Taraborrelli claims she knew — a lot.

“There were many senators and people who worked for the president who were really well aware of the conversations that Jackie had with JFK, in which she made it really clear that she knew what was going on,” Taraborrelli tells People.