A Sri Lankan mother-of-three who was killed in Australia by her estranged husband, had fled the family home with her children almost a decade earlier after he hit her with a hammer and stomped on her, a jury has been told.

Nelomie Perera, 43, was found dead in her kitchen in December 2022 after Dinush Kurera allegedly murdered her in what prosecutors alleged was a "sustained, brutal and vicious attack" with a hatchet and kitchen knife.

The 47-year-old has pleaded not guilty to the murder, and to assaulting his 17-year-old son.

Kurera has admitted he killed his wife, but claimed he did so to save his own life, his lawyers told Victorian Supreme Court jury on Wednesday.

"He grappled with her over the knife, in her murderous rage, and he defended himself and the deceased was killed," defence barrister John Desmond said.

"Rage met rage."

Ms Perera was found in a pool of blood with 35 separate injuries, after Kurera allegedly killed her in front of their children in December 2022.

Kurera, who was assessed by paramedics and taken to hospital, had no signs of any physical injuries, prosecutor Mark Gibson KC said.

Mr Gibson has alleged Kurera was fuelled by a "deep-seated hatred" for Ms Perera when he killed her, after she told him she wanted a divorce and he discovered she was seeing other people.

He said Ms Perera had discovered Kurera was cheating on her while he was on a trip in Sri Lanka and ended their marriage over the phone.

She told him he could no longer stay at their family home, organised a storage unit where she moved his belongings and was allegedly fearful about his return to Melbourne, Mr Gibson said.

About two days after he flew home, on December 3, 2022, Mr Gibson said Kurera purchased a 30cm crowbar and a fibreglass hatchet.

That evening Kurera drove to the family home in Sandhurst, in Melbourne's southeast, and used the crowbar to break through the fence while wearing dark clothing and gloves.

"Mr Kurera, under the cover of darkness, approached Nelomie, taking her by surprise as she was about to have a cigarette on the back patio area," Mr Gibson said on Tuesday.

He alleged Kurera struck his wife in the head with a hatchet, which Mr Desmond said Kurera denies, and their two teen children ran down to their mother's screams.

The family then moved to the lounge room where the estranged couple argued before Mr Gibson claimed Kurera again hit Ms Perera with the hatchet, which Kurera also denies.

Their 17-year-old son tried to run for help when Mr Gibson alleged Kurera chased him and hit him with the axe, which the accused man further denies.

Mr Gibson alleged Kurera, Ms Perera and their 16-year-old daughter moved to the kitchen where he grabbed a 30cm long kitchen knife and stabbed her.

But Mr Desmond said this was a "stark issue" for the jury to decide as Kurera claims Ms Perera came at him with the knife.

"Nelomie took the opportunity when it arose to get the kitchen knife and came at the accused in a wild rage, violently swinging this large kitchen knife at the accused, trying to kill him," he said.

"He did what any person would do and was entitled to do in those circumstances - he defended himself."

Ms Perera's sister Minoli gave evidence on Wednesday afternoon, describing an alleged history of violence perpetrated by Kurera.

The jury was told Ms Perera fled to her parents' home with her three children in 2013 after Kurera allegedly hit her with a hammer and stomped on her.

"She had bruises on her face and she was struggling to walk," Minoli said.

"She told me that she couldn't leave (Kurera) because of the children."

She said when Ms Perera caught her husband cheating on her with a woman in Sri Lanka he denied it and said "it was all in her head".

The trial continues.

(This story originally appeared in the Australian Associated Press)