Craig McDermott, who subjected his former partner to years of family violence, has been sentenced to 25 years in jail for her murder.

The 40-year-old was found guilty in May of killing Fiona Warzywoda outside her solicitor's office at a Sunshine shopping centre in 2014.

Ms Warzywoda had just finalised an intervention order against McDermott when she was stabbed six times.

In sentencing, Justice Jane Dixon said McDermott blamed his former partner for court orders preventing him access to their four children, after years of violence fuelled by alcohol abuse.

"You were driven by extreme anger and held Fiona responsible for the court outcomes," Judge Dixon said.

The day before she was brutally stabbed in front on shocked onlookers, Ms Warzywoda had finalised a family violence intervention order against him.

"You killed someone you said you loved," Judge Dixon said

"All that could avoided had you shown patience and restrain in the breakdown of the relationship.

"If you had obeyed those orders your children would still have a mother. You have irreversibly damaged the lives of your children."

The court heard in the lead-up to the attack, fuelled by anger and resentment, McDermott had made several threats towards Ms Warzywoda.

On the day before she was murdered, a court security guard overheard McDermott say "I'm going to slice her", as he left court.

The court was told McDermott's children heard him threatening to kill their mother with a pocket knife, which he kept in his car.

McDermott, who pleaded not guilty on the grounds of self-defence, will be eligible for parole in 20 years.

Vicious lunchtime attack lasted 30 seconds

Before a court hearing, Ms Warzywoda told protective services officers McDermott had told her "You're f*****".

Fiona Warzywoda separated from her partner two months before she was killed. ( AAP: Victoria Police )

However, the judge ruled the threats were said out of anger and frustration.

Judge Dixon said she was satisfied McDermott formulated the plan to kill on the day of the attack, and had run up to the mother of his children with a knife hidden under his clothes before viciously stabbing her.

The court heard he rained down blows on her even as she fell to the ground. The attack that lasted less than 30 seconds.

"You left her fighting for her life," Judge Dixon said.

'Fiona can now rest in peace': Brother

A large number of family members were in court for the sentence.

The couple had been together for about 18 years before breaking up just two months before the murder.

Ms Warzywoda was 15 and McDermott was 20 when they met.

Paul Judge, Ms Warzywoda's brother, said the family was happy McDermott got a "decent" sentence, and hoped it would help put an end to family violence.

"She'd bend over backwards for the kids, she was really just a fantastic lady," he said.

"Fiona can now rest in peace and we'll get on with our lives as well."

Her sister Jolene Warzywoda said she missed her every day.