Nigella Lawson has told a court she would rather be "honest and ashamed" than "bullied with lies" after revealing details of her past drug use.
The TV cook said she was "not proud" after admitting she has taken cocaine and cannabis but denied her admission was "damage limitation".
"I'm not proud of the fact I have taken drugs but that does not make me a drug addict or a habitual drug user," she said.
Nigella said she objected to stories "peddled" by her ex-husband Charles Saatchi, including that he was checking her nose for cocaine when he was photographed gripping her throat outside Scott's restaurant in central London.
"The fact is, I would rather be honest and ashamed... I wasn't going to be bullied with lies," she said.
"Mr Saatchi was not examining me for cocaine. That's a story he made up afterwards to clear his name."
Nigella was continuing her evidence in the fraud trial of two of her former personal assistants.
Wearing an all-black outfit, she was greeted by a huge pack of photographers, reporters and cameramen as she arrived for a second day at Isleworth Crown Court in west London.
Jurors were previously read an email sent to Nigella from Charles in which he said the defendants would "get off" on the basis that she was "so off her head" on drugs she allowed them to "spend whatever they liked".
Yesterday she denied being a drug addict and spoke of the "intimate terrorism" she suffered at the hands of her ex.
She said she first took the class A drug with her late husband John Diamond when he found out he had terminal cancer, and on another occasion later during her troubled marriage to Charles.
But the 53-year-old, who also admitted to smoking cannabis, said the idea that she is a "drug addict or habitual user of cocaine is absolutely ridiculous".
"I did not have a drug problem, I had a life problem," she said.
Francesca Grillo, 35, and her sister Elisabetta, sometimes referred to as Lisa, 41, are accused of committing fraud by abusing their positions by using a company credit card for personal gain.
Prosecutors claim the Italian sisters lived the ''high life'', spending the money on designer clothes and handbags from Louis Vuitton, Christian Dior and Vivienne Westwood.
The pair are accused of using credit cards loaned to them by the TV cook and her ex-husband to spend more than £685,000 on themselves between 2008 and 2012.
The Grillo sisters, of Kensington Gardens Square, Bayswater, west London, deny the charge against them.
Under cross-examination by defence barrister Karina Arden, representing Francesca, Nigella denied using her evidence to explain herself in front of "the world's press".
"I felt it was my duty to come," she said.
"I certainly felt it would be an unpleasant experience but that's not a good enough reason not to do one's duty.
"I prefer to keep my private life private."
Nigella denied lying to police when she disputed the drug allegations against her and said it was the "extent" of her drug use that was untrue.
"It was not true in that my ex-husband was saying that he was getting cocaine out of my nose at Scott's and that I had been completely off my head for 10 years," she said.
"I actually did say at the time it was the extent that was not true."
She told the court her first use of cocaine with John Diamond was in 1999.
Referring to her admission of drug use yesterday, Ms Arden put it to Nigella that it was "a case on your part of damage limitation".
She replied: "No, I was asked the question and I responded."
The celebrity cook, took issue with Ms Arden referring to her as "the lady of the house".
Repeating the term back to the barrister, Nigella said: "I don't think it is the job of a woman to run a house."
She said it was the job of herself and Saatchi.
When asked if the multimillionaire Saaatchi Gallery owner really had an interest in the house, Nigella said: "Absolutely. He would go round and point out marks he wanted removed.
"He is a person with a tremendous eye for detail."
Nigella said that among other duties, Francesca would organise Saatchi's frappuccinos and sew buttons on his suits.
Ms Arden asked if Francesca did the food shopping, to which Nigella replied: "I do a fair amount myself."
Ms Arden then said: "This is no criticism of you as a domestic goddess."
The court heard that Francesca took a number of holidays with Nigella's children and stepchildren, including trips to Paris, Berlin, New York, Los Angeles and the south of France.
Nigella said Saatchi was "very much a cash man" and would have given Francesca money to take on the trips for their children.
The food writer admitted there were "no written-down rules" about the use of Saatchi's company credit card by the PAs.
"It was known, because it was spoken, that they were not for personal use except if directed," she said.
Laughter broke out around the packed courtroom on a few occasions at some of Nigella's responses to Ms Arden's questions.
When Ms Arden was asking if a property owned by Saatchi was sold for £25 million, and Nigella said she was not aware of the exact sum, the barrister said the £25 million figure had been reported in the press, to which the TV star replied: "Then it must be correct."
Ms Arden told Ms Lawson that she shares her "penchant for things Italian", and said she did not mean that as a criticism.
Ms Lawson said: "I don't see how that could ever be interpreted by anyone as a criticism."
Earlier Ms Lawson said there had been a "feeling of sisterhood" in her home among the staff.
Describing Francesca, Ms Lawson said "there was some element of the fantasist" with her.
When asked about the designer clothes worn by Francesca, Ms Lawson said: "She always said they were knock-offs which I don't enormously approve of either."
She added: "She would say 'I got this from a website' or sometimes she would say it was a sample sale."
When Ms Arden suggested showing photographs to Ms Lawson, she said: "If they're about clothes I wouldn't bother because I'm not really very good on fashion."