This was a loveless marriage under deep strain in the weeks leading up to the bullets striking the President in Dallas in November 1963.
He continued to see Callas right up until he died, with friends noting that she had been the real love of his life, the book excerpt notes.
The photograph scandal was the final hit after years of public disputes between Jackie and Ari.
He gleefully boasted about his own dalliances, once telling Johhny Meyer: 'Everybody here knows three things about Aristotle Onassis.
In the summer of 1971, on the private Greek island of Skorpios, Settimio Garritano took a set of photographs that changed perceptions of the most debated woman in the world.
She had turned to the Greek shipping magnate for comfort after the death of her son Patrick at just two days old.