The email he wrote to the celebrity chef was read in full to jurors but, when asked if he believed allegations that Ms Lawson was a habitual cocaine user, the art dealer said: “I do not know.”
“If you ask me whether I actually knew whether Nigella ever took drugs, the answer is no,” Mr Saatchi told Isleworth Crown Court in west London, where his former personal assistants are on trial accused of fraud.
Italian sisters Elisabetta and Francesca Grillo are accused of using credit cards loaned to them by the celebrity couple to spend more than £685,000 on themselves.
Under intense questioning from defence barrister Anthony Metzer, Mr Saatchi refuted the suggestion that his former wife’s mind was so “addled” by drugs that she was not aware what she had or had not permitted the sisters to buy.
“Are you asking me whether I think that Nigella truly was off her head?” he asked. “Not for a second. Over this whole period, she was writing books very successfully and appearing on television shows.
“I have never, never seen any evidence of Nigella taking any drug whatsoever.
“I want to be helpful, but I genuinely have no real knowledge at all.”
Mr Saatchi listened as the email he sent to Ms Lawson on Oct 10 was read out. In it, he referred to his ex-wife as “Higella” at one point.
In the email, he wrote: “Nigella, I was sent these by a newspaper and I can only laugh at your sorry depravity.
“Of course now the Grillos will get off on the basis that you... were so off your heads on drugs that you allowed the sisters to spend whatever they liked and yes I believe every word the Grillos have said, who after all only stole money.
“But I’m sure it was all great fun and now everything is perfect — bravo, you have become a celebrity hostess on a global TV game show. And you got the Pass you desired, free to heartily enjoy all the drugs you want, forever. Classy.”
Questioned about the email by prosecutor Jane Carpenter, Mr Saatchi said: “I’m utterly bereft that this private email to Nigella has come back to haunt us both. That’s all I have to say.
“The stories that the Grillos were parading was that Nigella had a severe cocaine habit that stretched back a very long time for the entirety of our marriage.
“What I was speculating here was that the Grillos would use this as a defence.”
It is alleged that the Grillo sisters lived the “high life”, spending the money on designer clothes and handbags.
Referring to the atmosphere in the family home before the breakdown of his marriage to Ms Lawson, Mr Saatchi said: “It was a happy home where everyone just buzzed around happily.”
Mr Saatchi said that he was “utterly heartbroken at having lost Nigella” and said he wished this year had never happened.
When asked if he had adored Ms Lawson during their marriage, he said: “I adore Nigella now. I absolutely adore Nigella and I’m broken-hearted to have lost her.”
Referring to a seemingly violent incident outside Scott’s restaurant in London in June that preceded the marriage breakdown, Mr Saatchi said: “I was not gripping, strangling or throttling her. I was holding her head by the neck to make her focus, can we be clear? Was it about her drug use? No.”
Questioned about the drug-taking allegations, Mr Saatchi said: “It was hearsay. I personally have absolutely no knowledge that Nigella has ever taken drugs.”