The ex-wife of disgraced former British climate change minister Chris Huhne told her trial on Thursday that he had put pressure on her to admit a speeding offence on his behalf.
Vicky Pryce said she refused point-blank when Huhne asked her to take the speeding points, but a few weeks later she received a letter nominating her as the driver and "exploded".
Greek-born Pryce, a 60-year-old senior economist, said when she refused to sign the letter and admit the offence her husband told her she was being "ridiculous".
She said Huhne told her: "'It's ridiculous you're not signing it, just sign here'."
Pryce told Southwark Crown Court in London: "I had no choice at the time because he was standing there saying 'This is it, this is the nomination form, you have got to sign this now'.
"It didn't look to me like I had any choice at all in the matter so I took this pen and signed, protesting all the time, but I did it."
The political career of Huhne, a leading light in the Liberal Democrat government coalition partners who narrowly lost in the contest to lead the party, is in tatters after he changed his plea to guilty in the case on Monday.
A week earlier he had denied the offence and said he would clear his name.
He has been told he faces a prison sentence, but the trial of his wife has gone ahead.
The case concerns an incident in March 2003 when Huhne's BMW car was allegedly caught by a speed camera as he travelled between Stansted Airport near London and the capital.
The prosecution says Huhne was driving but wanted Pryce to admit the offence because he had previous speeding offences and would have been banned if he had taken the speeding points.
The jury has heard how emails between Pryce and a journalist she spoke to described the economist wanting to "nail" her ex-husband, and the court was played four phone calls where Pryce tried to get Huhne to admit the offence.
Giving evidence on Thursday, Pryce gave details of the couple's 26-year marriage, which ended in 2010 when Huhne told her he was having an affair with bisexual PR advisor Carina Trimingham.
Huhne announced the affair as the couple watched a World Cup match then told his wife he had 20 minutes to write a statement, before he left the house to go to the gym.
"At no time was there an apology or any concern about what it would mean for us," she said.
Huhne has said he will resign his parliamentary seat in Eastleigh in southeast England, triggering a by-election which could accentuate the tensions in the Conservative-Lib Dem coalition.
The trial continues.