The images, which were first published in the Sunday People, provoked a public debate about domestic violence among the rich and famous.
He dismissed the incident as nothing more than "a playful tiff" but then accepted a police caution for assault. He said he had done so to stop the incident "hanging over" them.
Charles Saatchi, who accepted a police caution for assault, told the Mail on Sunday he had "clearly been a disappointment" to his wife, adding the couple have "become estranged and drifted apart" over the last year.
Charles Saatchi told the newspaper,"I am sorry to announce that Nigella Lawson and I are getting divorced".
He added: "This is heartbreaking for both of us as our love was very deep, but in the last year we have become estranged and drifted apart."