Vicky Pryce has been found guilty of perverting the course of justice, in a judgement which raises questions about how much senior Liberal Democrats knew about the row before it hit the front pages.
The former wife of Chris Huhne tried to use a defence of marital coercion, saying she had been forced to take her then-husband's speeding points in 2003, but the jury issued a unanimous guilty verdict after 12 hours of deliberation.
Pryce looked open mouthed as the verdict was handed down.
The economist, who is 60 years old, was given bail at Southwark crown court but the judge warned her to be "under no illusions" about the sentence she would receive.
The decision means Huhne himself will soon join his ex-wife in court for sentencing, where they can expect a short custodial sentence. Huhne may get a shorter sentence for pleading guilty.
The case has raised questions about how much Nick Clegg and Vince Cable knew about the speeding points accusations.
Emails released by the Crown Prosecution Service now the trial is over show Pryce claimed to have confided about the speeding tickets to Miriam González Duránte, Clegg's wife, and to Cable and his wife during a dinner.
"Other possibility would be to tell NC [Clegg] or his close associates (having coffee with Miriam this PM) that the papers are on to him [Huhne] … (that also might have the added benefit of NC not wanting any more scandals and ease him out anyway ...)," Pryce wrote to Isabel Oakeshott, political editor of the Sunday Times.
In another email, she wrote: "Actually I had told Vince [Cable] and Rachel [his wife] about points before when the three of us were having supper about a month ago – they were horrified at the time but VC has probably forgotten it by now. He was v tired that night."
In a statement today, Cable said he has "no recollection" of the conversation.
The judgement brings to an end an extraordinary case which began when Huhne left Pryce to start a relationship with Carina Trimingham.
Pryce's decision to speak with journalists about the speeding points was interpreted as an effort to get back at her husband, but it ended up not only destroying his career but also probably sending them both to jail.
"I have no doubt as I definitely want to nail him. More than ever actually and would love to do it soon," Pryce wrote to Oakeshott.
Oakeshott texted Pryce: "The bottom line is that this story WILL bring Chris down, IF you are willing to go on the record about what happened with the minor risk that this carries."
Huhne's guilty verdict shocked observers after months of denials and triggered the Eastleigh by-election, which the Liberal Democrats won.
The political repercussions have been substantial. The by-election consolidated Nick Clegg's hold on power, sparked new rumours of leadership bids against David Cameron, saw a surge in support for Ukip and raised questions about Ed Miliband's ability to win votes in the south-east.
Pryce's first trial was thrown out after a series of questions by the jury prompted the judge to conclude they had fundamentally failed to understand the legal concepts they were being asked to pass judgement on.
Her testimony and the evidence revealed to the court painted a tragic portrait of a family being torn apart by the charges.