New York, September 26: Billionaire investor Warren Buffett feels that letting his late wife Susie walk out the door of their Omaha home was the biggest mistake he had ever made.

He revealed his feelings while discussing his personal life with Alice Schroeder, the author of a biography about him, entitled 'The Snowball'.

The 78-year-old admitted that he gave Susie plenty of reasons to leave, one of which was Katharine Graham, publisher of The Washington Post and Newsweek.

The investment genius told the author that Graham, a 59-year-old widow at the time he was 46, was smitten with him.

He revealed that they often holed up at Graham’s Martha's Vineyard mansion.

Schroeder writes in the book that Graham would not hide her flirtation, and toss her house key to Buffett at parties.

"(Susie) made it plain to several friends that she was furious and humiliated," but sent Graham a letter granting her permission to date her husband, the author writes.

"Kay showed the letter to people as though it let her off the hook," the New York Daily News quoted Schroeder as adding.

Buffett revealed that Susie began a romance with her tennis coach John McCabe, and in 1977, informed him that she was buying a small apartment in San Fransisco.

Meanwhile, expecting that Warren would fall apart without a woman to look after him, Susie arranged for attractive blond Astrid Menks to cook and clean for him.

Susie never divorced Warren, and after her death in 2004, the latter married Menks.

Buffett told Schroeder that Susie's departure could have been prevented.

“It was definitely 95 per cent my fault. ... I just wasn't attuned enough to her, and she'd always been perfectly attuned to me. She kept me together for a lot of years. ... It shouldn't have happened," he told the author. (ANI)