Her husband wanted bacon and eggs for breakfast, and Sally Challen complied. She set out to buy the items on an August morning in 2010.

But when she returned from the shop — near their home in a leafy village outside London — she became suspicious. She sensed that she had been sent on the errand only to get her out of the house, which she and her husband, Richard Challen, were planning to clear and put on the market in an attempt to start fresh after marital difficulties.

Challen, who was 56, checked her husband’s phone, discovering that he had just spoken to a woman from a dating site. When she asked him to explain, as documented in British media, the 61-year-old shot back coldly, “Don’t question me, Sally.”

She cooked him breakfast over the stove. She served him his bacon and eggs.

And then, as he ate, she retrieved a hammer from her handbag and struck him more than 20 times over the head. To hasten his death, she shoved a tea towel into his mouth. Wrapping him in old curtains and blankets, she left a note on his body that read, “I love you, Sally." She washed the dishes, got back into her car and returned to the nearby home that she and her 23-year-old son had moved into less than a year before, putting physical distance between her and her husband, the retired owner of a car dealership. They had met when she was 15 and had been married for more than three decades.

The next morning, Challen drove her son to work. As he stepped out of the car, she asked him, “You know I love you, don’t you?” Then, she set in motion a plan to end her life. She drove to Beachy Head, a chalky cliff overlooking the English Channel, and called her cousin to confess. She repeated the admission to a suicide prevention team and a chaplain called to the scene, where it took more than three hours to talk her back from the 500-foot edge, according to media reports at the time.

She was arrested on suspicion of murder, charged, convicted and sentenced in 2011 to life in prison with a minimum of 22 years, later reduced to 18.

Eight years later, her murder conviction has now been vacated in a landmark decision by an appeals court in London, which on Thursday ordered a retrial to weigh new evidence that the accused was herself a victim of sustained marital violence that impaired her mental health.

The case made legal history in Britain, marking the first time that a court had considered a defense based on what’s called “coercive control," abusive behavior designed to harm, punish or frighten a victim as a form of domestic violence.

“Thousands of voices will now rely on my mother’s case,” her son David, 31, said in an interview with The Washington Post.

Challen appeared at the appeal via a video link from HMP Bronzefield, a female prison about 10 miles from her former home in Claygate, a quiet suburb in Surrey, England.

She wept when she heard the decision.

Her legal team will now ask prosecutors to accept a manslaughter plea, while her son said they would apply for bail.

“She deserves her freedom,” he said. “She’s never had it, since the age of 15 when she first met my father."

David Challen and his 35-year-old brother, James, led a public campaign on their mother’s behalf, saying they had witnessed her torment at the hands of their father but didn’t know how to name it at the time.

“You’re going mad, Sally," he would tell her, the younger son recalled, according to Sky News. "You’re making it all up. You’re going mad.”

Challen, now 65, admits to killing her husband but denies murder, arguing that she has diminished responsibility because of the physical and psychological abuse to which he subjected her.

Her attorney, Harriet Wistrich, pursued that argument by pointing to a law approved in 2015 that recognizes coercive control as a criminal offense. Notably, the statute does not require that the abuse present an imminent lethal danger, an element that has been central to the use in U.S. courts in what some call the “battered woman’s defense.”

The decision affirmed in stark terms just how terribly marital violence matters and pointed to new understanding, in the era of the #MeToo movement, that not all injuries are external. It acknowledged, Wistrich said, how abuse and belittlement make themselves invisible by winding their way into the very fabric of female experience.

“Domestic violence isn’t just about black eyes and bruises and broken arms,” she said. “It’s complex and dynamic and fundamental.”

Shocking outbursts of violence did punctuate Challen’s mistreatment, Wistrich said, including a “punishment rape” after a male friend had said goodbye with a kiss on the cheek. Perhaps even more significant, though, was the psychological, emotional and financial pressure exerted by her husband to “mold her into his shape,” the attorney said. “It helps explain why someone at the age of 56, who loved her husband and had never committed a violent act in her life, could commit this somewhat extraordinary and quite brutal killing.”

Evidence of two mental disorders, presented by a forensic psychiatrist, had been absent from the initial trial in 2011, the judges reasoned. The court heard this week that Challen’s situation was equivalent to the anguish suffered by a “prisoner of war,” as Evan Stark, an American sociologist and forensic social worker who introduced the concept of coercive control in a 2007 book, testified, according to the Telegraph.

Charlotte Barlow, a criminologist at Lancaster University Law School who has worked to equip police officers with tools to counter coercive control, hailed the decision as a landmark, saying it “sends a message of hope to those who remain in abusive relationships.”

Women do not suddenly decide to seek revenge against their husbands, she said, but rather act in response to an “insidious web and pattern of abusive behavior, that in Sally’s case, occurred over a 40-year period.”

The pair met when Sally Jenney was 15 and Richard Challen was in his early 20s, the Guardian reported. She came from a traditional family, with four older brothers. Her father, a brigadier in the Royal Engineers, died when she was 6. Her mother didn’t think higher education was the right path for her.

When they were introduced by a friend of Challen’s, he was already selling cars. She grew loyal to him, and would arrive at his flat after school to do chores. He continued to see other women, according to the Guardian, and when she challenged him about it early in the relationship, he pulled her down the stairs and threw her out the door. Nevertheless, she married him in 1979.

He landed his own car dealership, while she looked after their two young sons and later got a desk job with the Surrey Police Federation.

She adored her husband, the younger son has said, even as he was unfaithful: “Seeing women, cheating on her, brothels.”

Neighbors in the close-knit community recalled how he would humiliate her in public, interrupting her or remarking on her appearance. In front of their children, he would call her “thunder thighs." When he went out, he would take away the phone, preventing her from communicating with the outside world.

In 2005, he ran afoul of the law when he crashed his Ferrari while racing in Belgium but told an insurance company that he had been ensnared in a hit-and-run near his home. He was arrested and charged with fraud, given a 51-week suspended sentence and ordered to perform 100 hours of community service.

Meanwhile, the besotted wife — who talked endlessly of her love for her husband — told doctors that she was suffering from stress, sleeplessness and loss of appetite, according to the Guardian. The newspaper reported that she finally began to seek distance after following her husband to a “massage parlor,” an establishment later busted for trafficking women.

Using money from her inheritance, she bought a home for herself and her younger son in 2009. But soon, she wanted Richard back, the Guardian reported. He agreed to reconcile on the condition that she signed a postnuptial agreement slashing her rights to the family home, valued at 1 million pounds, or about $1.3 million, and setting other severe requirements, including that she not interrupt him, according to the BBC.

Those conditions for their reunion were also on her mind, she would later tell police, when she returned to make him breakfast on the rainy Saturday morning that left him with blunt force trauma to the head.

"The whole thing was a game, let’s get one over on Sally again,” she said.

It wasn’t a game that she was equipped to play, her advocates argue, because of the mental state into which she had slipped, one in which she was entirely dependent on her husband. She wanted out, but instead wound up in a different sort of prison.