Rebekah Vardy has lost her High Court libel battle with Coleen Rooney in the so-called Wagatha Christie trial.
Mrs Rooney, the wife of former England footballer Wayne Rooney, conducted a sting operation in 2019, accusing Mrs Vardy online of leaking private stories about her to The Sun.
Mrs Vardy has always denied she passed information to the newspaper.
But on Friday, Mrs Justice Steyn ruled Mrs Rooney's accusation was "substantially true".
Mrs Vardy, who is married to Leicester striker Jamie Vardy, said in a statement she was "extremely sad and disappointed" at the judge's decision.
"It is not the result that I had expected, nor believe was just. I brought this action to vindicate my reputation and am devastated by the judge's finding... as for the rest of her judgement, she got it wrong and this is something I cannot accept."
She also said: "Please can the people who have been abusing me and my family now stop. The case is over."
Mrs Rooney said she was "pleased" the ruling had gone in her favour, adding "it was not a case I ever sought or wanted".
"I never believed it should have gone to court at such expense in times of hardship for so many people, when the money could have been far better spent helping others."
She added on Instagram: "Although I bear Mrs Vardy no ill will, today's judgement makes clear I was right in what I said on my Instagram post."
The judge said of Mrs Vardy that "significant parts of her evidence were not credible", while she added: "In my judgement, Ms Rooney was an honest and reliable witness."
Mrs Justice Steyn said it was "likely" that Mrs Vardy's agent at the time, Caroline Watt, "undertook the direct act" of passing information to The Sun.
But she added: "The evidence... clearly shows, in my view, that Mrs Vardy knew of and condoned this behaviour, actively engaging in it."
The judge found that Mrs Vardy had been "directing Ms Watt to the private Instagram account, sending her screenshots of Mrs Rooney's posts, drawing attention to items of potential interest to the press, and answering additional queries raised by the press via Ms Watt".
She also pointed out that "there were many occasions" when Mrs Vardy's evidence "was manifestly inconsistent" with other evidence, and "evasive or implausible".
Phone 'deliberately dropped'
During the case, the court heard that Ms Watt's phone had fallen into the North Sea while she was filming the Scottish coastline in August 2021 - so it could not be submitted as evidence.
But the judge said the likelihood that the loss of the phone was accidental was "slim".
"In my judgement, it is likely that Ms Vardy deliberately deleted her WhatsApp chat with Ms Watt, and that Ms Watt deliberately dropped her phone in the sea," she said.
She also said: "I have found that Ms Vardy and Ms Watt have deliberately deleted or destroyed evidence."
During the libel trial, Mrs Rooney sought to present Mrs Vardy as courting publicity and, along with her agent Caroline Watt, willing to pass lots and lots of stories to journalists.
In one exchange, Mrs Vardy told Ms Watt "I want paying" in relation to a potential story unrelated to the Rooneys.
The High Court judgement found this was an example of Mrs Vardy understanding the value of information.
Mrs Justice Steyn's damning judgement reveals the two prices that must be paid by those who bring - and lose - a libel claim.
Firstly, Mrs Vardy's legal bill will be enormous. It may be in the region of £2m once the bill comes in from Mrs Rooney's legal team.
But the true cost may be far greater.
Mrs Vardy can afford to pay the lawyers - but given the judge said she "deliberately deleted or destroyed evidence", that's a reputational hit that it will be very, very hard for her to recover from.
Mrs Justice Steyn concluded that Mrs Vardy had "a degree of self-deception" about her role in disclosing information to The Sun.
"Although significant parts of Mrs Vardy's evidence were not credible, my assessment is that she is genuinely offended by the accusation made against her by Mrs Rooney in the reveal post."
The judge said Mrs Vardy's actions were "it seems to me, unthinking rather than part of a considered and concerted business practice".
The so-called Wagatha Christie case centred on the viral social media post from October 2019.
In it, Mrs Rooney, said she had planted fake stories on her Instagram account, in an effort to find out who was leaking private information about her to the press.
After clamping down on her privacy settings to try and catch the perpetrator, Mrs Rooney said the only account which had viewed the stories, which later ended up in the Sun, was Mrs Vardy's.
Mrs Vardy, the wife of Mr Rooney's ex-international teammate Jamie, denied the allegation and brought the defamation claim.
'Terrible brand damage'
Media lawyer Jonathan Coad told the BBC the case had been "an absolute disaster" for Rebekah Vardy, and what made it "even more tragic is that four times Coleen really tried to settle this case".
He said Mrs Vardy had suffered "terrible brand damage" during the cross-examination by Coleen Rooney's lawyer, David Sherborne.
"More damaging, though, is that she's effectively been branded a liar," he added, explaining that Mrs Vardy had denied leaking stories under oath.
The case has raised issues about social media and libel laws, and how posting an allegation about someone online compares to publishing one in print.
Antonia Foster, a partner at defamation specialist law firm Carter-Ruck, told the BBC: "As this case has proven, you very much can sue on allegations published on social media.
"I suspect that despite the fact that Coleen Rooney is the victor today, she probably didn't anticipate that posting would cause the lengthy trial that it has done."
Mrs Justice Steyn said she accepted "the reveal post was on a matter of public interest... namely the undesirable practice of information, in the nature of mere gossip, about celebrities' private lives being disclosed to the press by trusted individuals".
But she added: "It was not reasonable to believe that it was in the public interest to publish the reveal post, without taking any steps to put the allegation to Mrs Vardy and give her an opportunity to respond."
Mrs Justice Steyn also said Mrs Vardy had faced "vile abuse" from members of the public following the reveal post.
'Stressful and distressing'
She added: "Nothing of which Mrs Vardy has been accused, nor any of the findings in this judgement, provide any justification or excuse for subjecting her or her family, or any other person involved in this case, to such vitriol."
She also said it was clear Mrs Vardy had found it "stressful and, at times, distressing" giving evidence.
But she said: "Nevertheless, I find that it is, unfortunately, necessary to treat Mrs Vardy's evidence with very considerable caution...
"Mrs Vardy was generally unwilling to make factual concessions, however implausible her evidence.
"This inevitably affects my overall view of her credibility, although I have borne in mind that untruthful evidence may be given to mask guilt or to fortify innocence."
Libel is the term used for defamation of a person through a permanent form of communication, mostly the written word - as opposed to slander, which is defamation through a more transient form of communication, usually speech.