Sally Challen, who killed her husband in a hammer attack at their Surrey home, will face a new trial after her murder conviction was overturned in a landmark decision.

Challen, 65, said she had killed her husband, Richard Challen, 61, in August 2010 after 40 years of being controlled and humiliated by him.

She was jailed for life for his murder following a trial at Guildford crown court in 2011.

But her conviction was quashed and a retrial ordered at the court of appeal in London on Thursday, after a panel of three judges ruled it was unsafe in light of new evidence that was not available at the time of her trial.

Speaking outside the court after the ruling, her son David Challen, 31, said: “It’s an amazing moment. The courts have acknowledged this case needs to be looked at again, as we have always said as a family.

“The abuse our mother suffered, we felt, was never recognised properly and her mental conditions were not taken into account.

“As sons, we get another shot for our story to be heard, the events that led to our father’s death to be heard, and for our mother to have another shot at freedom – a freedom she has never had since the age of 15.”

Challen, of Claygate, Surrey, who was separated from her husband at the time of the crime, hit him with a hammer 20 times.

She admitted killing the former car dealer, but denied murder claiming diminished responsibility. Her case was that she had been subjected to abuse and intimidation by her husband, whom she met when she was 15.

The prosecution case was that it was the action of a jealous woman who suspected infidelity, and she was found guilty of murder and jailed for life with a minimum term of 22 years, later reduced on appeal by four years.

She has so far served eight years of her sentence.

Quashing her conviction on Thursday, three senior judges ruled fresh evidence given by a psychiatrist undermined the safety of her conviction.

Challen, who attended the appeal over a video link from HMP Bronzefield in Ashford, Surrey, burst into tears as she heard the result and there were cheers and applause from relatives and supporters in the public gallery.

Challen will now face a retrial on a charge of murder.

Lady Justice Hallett, sitting with Mr Justice Sweeney and Mrs Justice Cheema-Grubb, said: “The court of appeal heard that, in the opinion of a consultant forensic psychiatrist, the appellant was suffering from two mental disorders at the time of the killing.

“This evidence was not available at the time of the trial and the court quashed the conviction and ordered a retrial.”

At a press conference, one of Challen’s lawyer, Harriet Wistrich, said: “Whatever may be the ultimate outcome, we have managed to raise awareness and a much deeper understanding of the concept of coercive control, which is such a recent one.”

Sally Challen’s son David and her lawyer Harriet Wistrich speak at a press conference after the conviction was overturned. Photograph: Mark Thomas/REX/Shutterstock

Wistrich said she had spoken to Challen immediately after the hearing. “It has not sunk in yet. She was obviously delighted that the appeal was won, but daunted by the prospect of what’s to come.”

She said this time the case would be “armed with great deal more concerning the context of how Sally came to act”. She had been portrayed as a jealous wife in her first trial, she said, adding: “I think that picture is now turned on its head because of our understanding of coercive control.”

The case was also supported by Challen’s other son, James Challen, and the campaign group Justice for Women, which had run a high-profile campaign ahead of the appeal.

Challen’s legal team is expected to pursue a bail bid at a future crown court hearing.

The court ordered Challen will have to have the fresh murder charge put to her within two months.