'I wanted to wring Bill's neck'

Hillary Clinton has admitted for the first time that she nearly divorced President Clinton after his affair with White House intern Monica Lewinsky.

In her new biography, to be published next week, she calls the decision to stay married to Clinton one of the two "most difficult decisions I have ever made".

Details of the book - which is expected to sell over a million copies with its first printing alone - were leaked last night ahead of a massive publicity campaign that includes an interview with ITN's Sir Trevor McDonald next week.

Until now the former First Lady, who was elected as a US Senator for New York nearly three years ago, has stayed silent about the Lewinsky scandal - which led directly to the President's impeachment hearings and sordid details of oral sex in the Oval Office.

Mrs Clinton says that at first she believed her husband's denial of the affair, putting it down to a "vast right-wing conspiracy" for nearly six months after it was first made public.

"For me, the Lewinsky imbroglio seemed like just another vicious scandal manufactured by political opponents," she says.

But she reveals that on the morning of 15 August 1998, the president woke her up, pacing at the bedside in the White House and he "told me for the first time that the situation was much more serious than he had previously acknowledged".

He then told her he was ashamed and knew she would be angry. "I could hardly breathe," says Mrs Clinton. "Gulping for air, I started crying and yelling at him, 'What do you mean? What are you saying? Why did you lie to me?'

"I was furious and getting more so by the second. He just stood there saying over and over again, "I'm sorry. I was trying to protect you and Chelsea."

Later, Mrs Clinton says, she could not believe he would risk their marriage and family for a fling. "I was dumbfounded, heartbroken and outraged that I'd believed him at all."

She says the president began to cry after she told him he would have to confess to their daughter Chelsea, then a teenager.

But she decided in the end that she still loved him, although "as a wife I wanted to wring Bill's neck". In what may have been the low point of the marriage, the couple took a hol iday that summer in Martha's Vineyard, where the tensions between them were visible to the world's media.

"Buddy the dog came along to keep Bill company," she says. "He was the only member of the family who was willing to go."

At the time she felt "nothing but profound sadness, disappointment and unresolved anger. I could barely speak to Bill and when I did, it was a tirade. I read. I walked on the beach. He slept downstairs. I slept upstairs."

In time, Mrs Clinton says, the couple were brought back together over her plan to run for the Senate - a decision which she says was as difficult as staying with her husband.

Her biography Living History is one the most eagerly anticipated political memoirs ever published, with Mrs Clinton getting a £5 million advance for her version of the couple's eight years in the White House.

Of the other controversies of the Clinton presidency, including the Whitewater land scandal that led directly to the appointment of special prosecutor Ken Starr, Mrs Clinton only admits "public relations mistakes", adding: "Whitewater never seemed real, because it wasn't."