Revealed: Marilyn called Jackie to confess JFK affair...

de bene esse: literally, of well-being, morally acceptable but subject to future validation or exception

Marilyn Monroe called Jackie Kennedy at the White House and confessed she was having an affair with her husband, to which the First Lady responded 'that's great... I'll move out and you'll have all the problems,' according to an explosive new book.

In 'These Few Precious Days: The Final Year of Jack with Jackie,' author Christopher Andersen claims Jackie 'knew everything' about Jack's cheating and turned a blind eye, but his relationship with Marilyn 'seemed to bother her the most.'

And she was right to fear the bombshell actress, because Marilyn's sights were firmly set on becoming the President's second wife. 

Affair: A new book claims Marilyn Monroe, pictured with JFK, called Jackie Kennedy and confessed she was sleeping with the President

Marilyn, who long grappled with psychiatric and emotional problems as well as drugs and alcohol, was convinced JFK was about to leave Jackie for her, her friend Jeanne Carmen reportedly revealed.

'Can't you just see me,' she asked Carmen, 'as first lady?'

According to excerpts of the book, published by The New York Post today, Peter Lawford claimed Marilyn called Jackie and told her she was sleeping with Jack, and that he'd allegedly promised to leave his family for her.

'Marilyn, you'll marry Jack, that's great,' Jackie responded, according to the account. 'And you'll move into the White House and you'll assume the responsibilities of first lady, and I'll move out and you'll have all the problems.'

Revelations: The revelations are contained in the explosive book 'These Few Precious Days,' pictured

Andersen writes JFK's Air Force aide, General Godfrey McHugh, revealed early on that 'Jackie knew about his women' and her friend Ralph Martin agreed. 'You know, in the end Jackie knew everything. Every girl. She knew her rating, her accomplishments . . .'

However, she didn't take his cheating lightly.

Jack's close friend, George Smathers, said Jackie was 'damn mad' about his fooling around, but she was willing to look the other way as long as he was careful and didn't humiliate her.

Jackie reportedly feared her own sexual inadequacies were pushing Jack into the arms of other women.

Jackie knew: The book claims that Jackie, pictured left with JFK and daughter Caroline in 1960, knew about his affairs, but his relationship with Marilyn Monroe, right, concerned her most

But she complained of the President's love-making to her long-time confidant Dr. Frank Finnerty, claiming 'he just goes too fast and falls asleep.'

Aside from the ladies, Andersen offers a fascinating insight into JFK's dependence on drugs.  His physician Max Jacobson, known as Dr Feelgood, administered high-dosage amphetamine shots laced with steroids to the president on a regular basis, the book claims, and even the first lady. Dr. Max's four-times-weekly injections worried other physicians who believed they might react with the dozen or so other drugs Jack was taking for his other health woes.

Gore Vidal reportedly said he was 'horrified' to learn Dr Feelgood was treating the President and, according to the book, told Jackie to 'Watch out' because 'Max drove several people mad.'