Nigella Lawson has been called a "habitual criminal" by her ex-husband, who also threatened to sue her if she didn't front up to the fraud trial of her former assistants.
The celebrity chef will be a key prosecution witness, along with her ex-husband Charles Saatchi, in the trial of two former aides who are accused of defrauding the couple out of more than £300,000 (NZ$600,000).
A judge has ruled that trial of Francesca and Elisabetta Grillo can go ahead, despite Saatchi suggesting his ex-wife authorised their spending when she was "off her head" on drugs, the Telegraph reported.
The court was also told Saatchi threatened to sue his ex-wife if she refused to give evidence in the trial.
Saatchi's lawyers wrote a pre-action letter to Lawson in October after she indicated she was reconsidering whether to give evidence in the trial of Elisabetta, 41, and Francesca, 35.
The Grillos claimed Lawson gave consent ''expressly or implicitly'' to spend freely on the company credit cards while she was high.
The four-year scam only finally unravelled when an accountant spotted that the pair were spending £50,000 (NZ$100,000) a month, it was claimed.
Jane Carpenter, prosecuting at Isleworth Crown Court, said they claimed their ''exorbitant'' spending was in exchange for silence about Lawson's alleged cocaine habit, the Daily Mail reported.
"The defendant's case is that Ms Lawson's alleged drug use and the defendants' knowledge of it, materially affected Ms Lawson's attitude to the defendant's spending."
But she said it was ridiculous to claim the couple approved the spending. She said the two sisters were fraudsters.
The duo had worked for Lawson for more than a decade and were treated as trusted members of the family who lived with them rent free and went on family holidays.
But over four years between 2008 and 2012 they fraudulently used the company credit card to splash out on luxury outfits, holidays and gifts to themselves, the court was told.
Saatchi, 70, is expected to give evidence for the prosecution overnight NZT, while his former wife may take the witness stand a day later.
Lawson has meanwhile broken her silence on Twitter for the first time since the drug claims surfaced.
— Nigella Lawson (@Nigella_Lawson) November 27, 2013
And #teamNigella sprang into action, with thousands of retweets and messages of support coming in from around the world.