'I thought he was going to change', says accused killer

 David Walsh and his killer, former fiancee Cathrina Cahill who is now awaiting sentencing.

David Walsh and his killer, former fiancee Cathrina Cahill who is now awaiting sentencing.

A Wexford woman who killed her fiance in Sydney has told a judge she did not leave the "controlling and fairly unpleasant" man as she loved him dearly.

David Walsh said he would change but would revert back to his bad behaviour, Cathrina Cahill, 27, told her sentencing hearing.

She was giving evidence on Tuesday in the New South Wales Supreme Court after pleading guilty to the manslaughter of Mr Walsh, who she stabbed once in the neck in the early hours of February 18, 2017, at their home in Padstow, south-west of Sydney.

"I honestly thought he was going to change. He was someone I did love and adore," she told the court.

Cahill, whose guilty plea was based on diminished responsibility due to an abnormality of the mind, previously gave evidence about repeated violence by Mr Walsh.

This included punching strangers and biting her all over her body, while he also accused her of her sleeping with other men and deleted texts from her phone, the court heard.

She had packed her bags many times to leave him, but Mr Walsh would tell her everything was going to be different, Cahill told the court.

She said: "He would be making me dinner, buying me flowers, buying me a teddy bear, but after two to three weeks it would go back to the way it was."

She agreed with Justice Peter Johnson that her evidence revealed a "pretty stormy relationship" and that Mr Walsh might be seen to be a "controlling and fairly unpleasant person".

But she said she stayed with him as she "loved him very dearly".

The fatal attack occurred when an intoxicated Mr Walsh launched an unprovoked attack on a man invited into the home by Cahill and the two other female housemates.

Cahill, who also had been drinking, was punched by her fiance when trying to stop the attack, before she took out a "large, very sharp, bladed knife" from the cutlery drawer and stabbed him.

Cahill's barrister James Trevallion said there was no evidence his client had ever struck Mr Walsh without any provocation and noted she was smaller than him.

He submitted she had no intention to kill, the stabbing had involved a single blow and Mr Walsh was the one who initiated the violence.

Justice Johnson, who said the case involved "unusual features" such as a "type of two-way domestic violence", will sentence Cahill on December 12.