After weeks of pressure from Conservatives and some newspapers over Mr Cook's relationship with Ms Regan, Mrs Cook's patience appears to have snapped.
In a statement yesterday afternoon she said: "The stories currently running in the press with regard to the Foreign Secretary are trivial and should be laid to rest so that he can get on with his job, which he does well.
"We have reached an amicable settlement with regard to the divorce and now wish to look to the future and not the past," she said.
The statement followed remarks by Mrs Cook, published in yesterday's Sunday Times, that the Foreign Secretary was "not a person I know any more."
She was reported as saying his recent remark that he had known more happiness in recent months than he could remember was "a cruel slight."
"I think it's just to put a spin on it, to make it look good - that this business is the result of mad, passionate love, whereas it wasn't really, it was the making of a bad situation.
"I think if nothing had been found out he would be going along stringing the two of us along," she said.
Yesterday no fewer than three Cabinet ministers defended Mr Cook. On the BBC's Breakfast With Frost programme the Deputy Prime Minister, John Prescott, said he had spoken to the Foreign Secretary to give him his support. The saga should not divert attention from more important issues such as Iraq, he added.
"I've had talks with Robin; so many of our ministers have as well. I mean these are matters that are private issues, they cause great concern and of course you want to give support to colleagues ... It's a price you pay for being in public life, unfortunately," he said.
George Robertson, the Defence Secretary, said there was no question of Mr Cook being "unfocused" on his job.
"I frankly don't think that it is right that we should be diverted by matters which everyone will consider to be of minor detail at this important time for Britain and the world," he said.
Chris Smith, the Secretary of State for Culture, Media and Sport, said he believed Mr Cook would continue to do a good job as Foreign Secretary for a long time to come.
"Of course we have to make sure that every government ministry is acting with proper probity and that the right procedures are being followed and that we're being honest in our dealings with the public.
"But beyond that, let's get serious about the important things," he said.
Aides to Mr Cook were also letting it be known that he had received strong support from the Chancellor, Gordon Brown. Despite past differences the two men had a drink and a chat together last week, they said.Reuse content