The son of Borce Ristevski says he told his father’s legal team he would air the accused’s family secrets if he took the stand in a Supreme Court murder trial, the day before Mr Ristevski unexpectedly admitted killing his wife.

It comes as family of Karen Ristevski expressed their relief at hearing – at last – the truth about their beloved Karen from the mouth of the only suspect in the suspicious disappearance.

Mr Ristevski had been committed to stand trial for the murder of his wife, and had repeatedly denied any involvement in the death.

But on the eve of proceedings to empanel the jury for the trial, the case took a twist when the 54-year-old father’s legal team told the court their client wished to plead guilty to manslaughter.

The Ristevski mystery had gripped the nation since Karen, 47, disappeared from her million-dollar Avondale Heights home in suburban Melbourne in June 2016.

Ms Ristevski’s brother Stephen Williams rushed to the court on Wednesday to witness part of the proceedings and spent the afternoon quietly coming to grips with the outcome.

“It’s been a whirlwind day,” Mr Williams told The New Daily.

Karen Ristevski with brother Stephen Williams. Photo: Stephen Williams

Still digesting the news, Ms Ristevski’s aunty Patricia Gray said she would need to wait until after sentencing before being able to articulate her views on the shocking crime.

In Ms Ristevski’s birthplace, New Zealand, her cousin Stephen Richardson said the fact that family and friends had been lied to by someone they had trusted was a double blow after losing a beloved woman.

Relatives, including the couple’s daughter Sarah and Ms Gray, had stood with Mr Ristevski during heartfelt, desperate public pleas for information about the missing woman.

“Standing right next to her is Borce – knowing that Karen is never coming back,” Mr Richardson said.

“The No.1 victim is of course Karen, but Sarah is a victim and [Mr Ristevski’s son] Anthony is a victim too.”

Borce and Sarah Ristevski made a public appeal for information about Karen in July 2016. A Mr Ristevski walked off after he was asked if he killed Karen. Photo: AAP

He added: “Even though it’s closure for the family, it’s hard.

“The hard part for me was that for Karen’s mother and father [who died before she disappeared], it was all about family – it was a lovely family,” Mr Richardson said.

“So to know that someone in her own family did this, that’s hard.”

Ms Ristevski’s stepson, Anthony Rickard, described it as a “good day”.

“Things are turning around for a change,” Mr Rickard said.

Mr Rickard, who grew up living with his father and stepmother, told The New Daily he had on Tuesday told his father’s legal team he would air family secrets during the impending murder trial.

Mr Ristevski’s son Anthony Rickard has struggled with addiction and has a criminal record, but says he is trying to move on with his life. Photo: Anthony Rickard

Mr Ristevski’s son was one of dozens of witnesses subpoenaed to appear at the trial.

He has previously alleged he’d had an improper relationship with his stepmother, a claim Victoria Police became aware of during the missing person’s case.

“I said I would stand up there and tell them all about what would happen behind closed doors,” Mr Rickard said.

“It would have put holes in his pride.”

The manslaughter plea was the most significant breakthrough in understanding what happened to Ms Ristevski since her body was found more than two years ago in bush north west of the city.

Patricia Gray, the aunt of Karen Ristevski, arrives at Melbourne Magistrates Court on Tuesday. Photo: AAP

Family members said they were relieved they would now not be required to testify at a trial or be cross-examined by the defence.

Mr Ristevski initially told police his wife had walked out after an argument about money and the couple’s Bella Bleu boutique clothing business.

But police tracked Ms Ristevski’s phone to the north of the city and found CCTV of her Mercedes-Benz being driven on the day she supposedly left home on foot.

Mr Ristevski will be sentenced at a later date.