Bill Clinton's worst day in office came when he admitted to his wife the affair with a White House intern that would threaten his marriage and his presidency, the US former president said in a television interview promoting his memoirs.

His confession to Hillary Clinton came two days before Clinton was to testify before a grand jury in August 1998 in an investigation that would lead to his impeachment, he said in an hour-long interview on CBS' "60 Minutes".

"I had a sleepless night and woke her up and sat down on the side of the bed and just told her. And it was awful," Clinton said. The interview was the first to air on television to promote the book "My Life."

"She looked at me as if I had punched her in the gut," Clinton wrote.

The renewed focus on the White House sex scandal may be starting to test Clinton's patience.

London's Sunday Telegraph reported that Clinton lost his temper when repeatedly asked about his affair during a BBC program to air on Tuesday.

The Telegraph quoted an unnamed BBC executive who saw the interview as saying Clinton "is visibly angry."

Clinton has kicked off afull-throttlepublicity campaign to sell his 957-page memoir, which goes on sale on Tuesday.

The launch includeshigh-profileinterviews, alavishbook party for a thousand guests in Manhattan on Monday and nonstop book signings and television appearances throughout the week.

While publisher Alfred A. Knopf has received more orders than the 1.5 million copies of the book's first printing, early reviews were tough on the former president's effort.

In a front-page review, The New York Times called it "sloppy, self-indulgent and ofteneye-crossinglydull -- the sound of one manprattling away."

"In many ways, the book is a mirror of Mr. Clinton's presidency: lack of discipline leading to squandered opportunities; high expectations, undermined by self-indulgence and scattered concentration," the Times wrote.

(Agencies)