An Australian woman says her life was in danger when she stabbed her husband, dismembered his body and disposed of it in garbage bags.

Nirmeen Noufl, 55, pleaded guilty to her husband's manslaughter on Wednesday after prosecutors decided to no longer pursue a murder case.

"All my life ... he just treated me like shit, spat at me," she told a confidante after the death in May 2023.

"I had enough."

Agreed statement of facts tendered after her NSW Supreme Court plea said her 32-year marriage was marred by domestic violence and reported infidelity from her husband Mamdouh Noufl.

Mr Noufl held conservative Islamic views and was controlling of his wife, who has been receiving treatment for depression and post-traumatic stress disorder for years, according to the court documents.

Just days before his death in their Greenacre home, he told his wife he had met a woman in Egypt years earlier whom he planned to marry, but denied Noufl's request for a divorce.

On the day he died, he signed over power of attorney to Noufl, in what agreed facts state was a normal arrangement between them to facilitate the management of their overseas interests.

Noufl told psychiatrists when her husband returned home later that day, they got into an argument and he assaulted her, choking her as he pinned her to the ground.

She said she felt like her life was in danger when she grabbed a nearby tool and fatally stabbed Mr Noufl once in the chest.

Over the next two days, the court documents state she dismembered her husband's body and placed his body parts into garbage bags which she then put in bins across several suburbs in western Sydney.

Mr Noufl's remains have never been recovered.

Noufl was to face a NSW Supreme Court trial this week after pleading not guilty to murder.

But the trial was delayed at the last moment, before Noufl admitted the alternative charge of manslaughter on Wednesday.

She had a blank expression as she beamed into the courtroom from a custody cell and entered her pleas.

Prosecutors conceded they could not disprove her version of events and accepted her plea of guilty to the lesser charge.

Noufl had a cut on her face, a bleeding lip and a swollen face when she was seen by a witness the day after killing her husband, according to court documents.

When asked why she had killed him, the agreed facts state Noufl told a confidante it happened in the moment when he was laughing at her as they fought.

"I have been trying to fight for us to be normal and to ignore the voices in my head," Noufl said, according to court documents.

"I'm sorry and I regret it but I genuinely believe it didn't happen and I don't know how I did it."

Noufl told her husband's family he didn't want to talk to anyone because he was embarrassed and ashamed about his affair.

He was reported missing two months after his death but Noufl denied any knowledge of his disappearance when approached by police.

She admitted herself to the acute mental health ward at Bankstown Hospital days before she was arrested in October 2024.

Noufl is expected to appear in person for a sentence hearing on September 14.