Something inside Sally snapped.
She went to her handbag, took out a hammer she can't remember putting there and hit him almost 20 times over the head until he was dead, stuffed a tea towel in his mouth and wrapped his body in a curtain.
The following day, she drove her son David, then 23, to work before driving to cliffs near their home with the intention of throwing herself off the edge. Hours later, she was talked down by a suicide prevention team.
At trial in 2011, Sally, then 56, was convicted of murder, painted as a vengeful, manipulative wife and given a 22-year life sentence.
It was a portrayal of a woman her son David Challen, now 32, didn't recognise, and a trial which hid the true character of his dad.
But David didn't have the vocabulary to describe the truth about his parents' relationship, leaving him feeling helpless.
"We didn't have the language, it all sounded so tit-bitty. Each incidence by itself doesn't sound like enough," David told news.com.au.
Then, in 2015, David learned two words that would change his life – and the fate of his mum: "coercive control".
That same year, England and Wales became the world's first nations to criminalise "coercive control" making it an offence punishable by up to five years in jail.
All of a sudden, David had a name for what he had watched his mum endure her entire life.
"If I'd have heard that term sooner, I'd have marched my father down to the police station, I swear to God," David says.
"This would never have happened. It is society's failing that my father lost his life and my mother suffered this abuse."
FERRARIS AND TOPLESS MODELS
Coercive control perfectly described the psychological abuse David's mum had endured at the hands of her husband since she met him aged just 15 years old.
At the time of his death, she had endured 31 years of her husband's philandering, brothel visiting, lying and gaslighting; encouraging Sally's complete dependence on him while humiliating, isolating, controlling, demeaning, fat-shaming and bullying her until she finally broke.
When Richard wanted sex, Sally would be sent upstairs to prepare because he hated seeing her naked. She'd be instructed to wash because he claimed she smelled, even after a doctor assured her she didn't.
He restricted the family from watching TV to save money, which he spent on a Ferrari. He posed with topless models on that Ferrari for a Christmas card he sent out.
When Richard saw his oldest friend give Sally a peck on the cheek as he said goodbye, he took her upstairs and raped her. He'd rape her continually throughout the marriage.
BID FOR FREEDOM
With this new criminal context, and against all odds, Sally won her appeal for a retrial, one championed by David and spearheaded by lawyer Harriet Wistrich who founded Justice for Women. It's the first time coercive control has been presented as a partial defence for murder.
In June this year, her murder sentence was quashed on the basis of diminished responsibility and a retrial wasn't pursued because the crown, eventually, accepted Sally's plea to the lesser charge of manslaughter.
She'd already served the length of a manslaughter sentence, so Sally Challen heard the words her family had fantasised about for almost nine traumatic years: You are free to go.
The landmark case captured the attention of the UK for months, and has opened discussion in Australia on whether coercive control should be criminalised.
STARTING AGAIN
After eight years and seven months in prison, Sally walked free three months ago.
The day she left prison David describes as like a scene from a film: this small, upright, well-spoken woman with a blonde bob, dwarfed by huge gates and fences doing a long walk with all her possessions in her hands. Prisoners pressed their faces up against windows; some prison guards were actually crying.
Shortly afterwards, a police officer involved in the case called to congratulate her and others did too.
The next few nights were punctuated by the dinners Sally had craved: Indian, Chinese, a classic roast. Her first fresh strawberry in almost a decade.
"It struck me then, this is the first time her entire life, since she was 15 years old, my mother has been able to walk around the world a free adult woman, able to do what she wants without asking permission – first from my father, then from prison guards. The first time. Aged 65.
"You get to start again," David says, smiling. His brother has just had his first child so Sally gets to be a grandma to her newly-born grandson. "Serendipitous timing," David says. "She wants to do so much, a million miles per hour."
LEGACY OF TRAUMA
David cannot deny, though, that their relationship now is different. I note that he always calls Sally his "mother" – never "Mum".
It's difficult to say whether this is middle class formality, or a survival technique when he felt no choice but to distance himself slightly from her while she was imprisoned.
"I have a new relationship with my mother – we're trying to explore how that is," he says. "She wants to be 'Mum' again but we're adults now. I was 23 when she went inside. She's missed my 20s."
Their mother-son relationship isn't cut and dry now, he confesses. "As much as I've always spoken out for her it's a hard thing to build that relationship back up again – I've felt very alone for the last seven years." He pauses and adds: "But she's felt very alone, too."
Australia has played a key part in the Challens' story. Richard and Sally Challen previously lived there and, just before Richard died, were planning to return as part of their reconciliation as a couple.
Around that time, Richard emailed Sally listing his terms of her return: "When we go out together, it means together. This talking to strangers is rude and inconsiderate. You will give up your constant interruptions when I am speaking."
David now sees Australia as a chilling, final way for Richard to completely isolate Sally from everyone who loved and was concerned about her in the UK. But it also holds happier significance.
Richard's Australian sister-in-law, Trish – his late brother's wife – was consistently supportive of Sally's appeal case. Even his own side of the family attested to his coercive control.
Now, for the first time, the family can look to the future with optimism.
"Christmas has been horrific for years, and to be together like this for the first time, it just makes me immensely happy" David says.
WHERE TO GET HELP:
If you are worried about your or someone else's mental health, the best place to get help is your GP or local mental health provider. However, if you or someone else is in danger or endangering others, call 111.
If you need to talk to someone, the following free helplines operate 24/7:
DEPRESSION HELPLINE: 0800 111 757
LIFELINE: 0800 543 354
NEED TO TALK? Call or text 1737
SAMARITANS: 0800 726 666
YOUTHLINE: 0800 376 633 or text 234
There are lots of places to get support. For others, click here.
