Cancer-stricken Elizabeth Edwards is telling pals that John beat her during a horrific marriage-ending fight, The ENQUIRER has learned exclusively.

"John lost his temper big-time," revealed a close friend of Elizabeth.

"She has the divorce papers drawn up, but she can amend them to charge John with domestic violence.

"She’s holding that over his head right now – and he’s scared. Elizabeth is in control."

Elizabeth privately disclosed all the shocking details of the alleged attack, says a close friend.

The friend spoke in detail about the terrifying incident – and passed a lie detector test regarding the shocking fight.

"John beat me," Elizabeth had told the friend.

Other sources confirm that the couple’s furious confrontation was the "final straw" in 60-year-old Elizabeth’s decision to end their 32-year marriage.

The disgraced politician has amassed a long and shameful history of denying The ENQUIRER’s stories about his cheating and his love child. But on Jan. 21, the former presidential candidate finally admitted paternity of his 2-year-old daughter Frances by mistress Rielle Hunter, and a distraught Elizabeth confirmed that the couple had officially separated.

The alleged beating ended any hope that the Edwards marriage could continue.

The friend reveals Elizabeth said: "When he (John) made the decision to hit me, it was over."

John did not respond when The Enquirer asked him to comment on the allegation he beat his wife.

Another source revealed: "Elizabeth has slapped John in the past during fights over his extramarital affair with Rielle.

"She was so tormented by John’s cheating and lies that she lashed out physically at him many times, even slapping him. On a couple of occasions, when the fights became heated, she grabbed him by the shoulders and screamed, ‘Why, why, why?!’

"Elizabeth would break down in tears and try to make John explain why he was throwing his family and political life away.

"During one of the confrontations, Elizabeth grabbed his arms and shook him so hard that John had to restrain her."

But the fighting escalated – and the ugly incident that "happened around the Christmas holidays turned out to be a violent, marriage-ending fight," said another source.

For the full shocking story you won’t find anywhere else pick up the latest Enquirer now! 
PLUS: learn the real reason cops remain silent after their midnight visit to the Edwardses mansion!