The tension grew as a Russian ship approached the U.S. quarantine around Cuba.
"The only thing I can think of what it was like, it was like an election night waiting, only much worse," she said. "Then finally, some ship turned back… then that was when you heaved the first sigh of relief."
JFK had prepared for the missile crisis with the humiliating defeat at the Bay of Pigs at the start of his term.
The young president had learned almost immediately upon taking office that he had inherited from the Eisenhower administration an army of Cuban refugees and plans for an invasion. But Kennedy determined that the U.S. would not be involved in fighting and withdrew planned attacks by the U.S. Air Force.
The subsequent offensive in April 1961 was a disaster. The CIA trained Cuban invaders quickly were defeated at the Bay of Pigs, with hundreds shot and killed, and the survivors rounded up and imprisoned.
It was a bitter start to the president's term and although Kennedy was a decorated veteran of World War II, he was badly shaken by the loss of life and the wreckage of the Cuban force. It was one of only three times Jacqueline Kennedy saw her husband cry.
"He came back over to the White House to his bedroom and he started to cry, just with me…..Just put his head in his hands and sort of wept," she recalled.
"All those poor men who you'd sent off with their hopes high and promises that we'd back them and there they were, shot down like dogs or going to die in jail," she said.
Presidential historian Michael Beschloss, who wrote the introduction to Mrs. Kennedy's oral history book, says that Kennedy was not adequately prepared to take on the competing forces of the presidency when confronted with plans for the Bay of Pigs invasion.
"He was in a way, a sitting duck for the CIA to say, 'We've got this great plan to invade Cuba.' He did not yet have the kind of knowledge that would have allowed him to say, 'This is going to be a failure,'" Beschloss says.
The president subsequently addressed the nation and took responsibility for the fiasco. In what would be almost unthinkable in today's political climate, his approval rating soared to 81 percent.