Cathrina "Tina" Cahill also told her sentence hearing she believed David Walsh every time he said he would change but he always returned to his bad behaviour after a few weeks.

She was giving evidence on Tuesday in the NSW Supreme Court after pleading guilty to the manslaughter of her 29-year-old fiance.

She stabbed Mr Walsh once in the neck in the early hours of February 18, 2017, at the Padstow home they shared with two other Irish nationals.

Cahill was originally charged with murder, but the Crown accepted her plea to the less serious charge on the basis of substantial impairment due to an abnormality of the mind at the time.

Prosecutor Nanette Williams on Tuesday noted Cahill told police in September 2015, after an AVO was issued against Mr Walsh to protect her, that she held no fears against him.

"I was in fear of getting in more trouble from David if I told the truth," she said.

"He would call me a rat and a dog."

She agreed she also told police Mr Walsh was not a risk to her in any way, but she said she was trying to protect him.

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

"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 they had 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 "I loved him very dearly" and he did have some good features.

The hearing continues.

Australian Associated Press