THE family of slain pregnant mum Kirralee Paepaerei, stabbed 49 times by partner Josh Homann while carrying their daughter, has described the killer as "a devil".

Eight of Ms Paepaerei's grieving relatives told the NSW Supreme Court on Friday of the distress caused by Homann, who listened in the dock, his head bowed.

Some relatives wore purple shirts with a photograph of Ms Paepaerei and an ultrasound image of the victim's unborn daughter with the words "Taken with Mum".

Homann was found guilty in March of the violent 2015 stabbing murder of Ms Paepaerei, his partner of two years who was seven months pregnant with their child.

Homann stabbed Ms Paepaerei 28 times in the face including wounds to her jugular arteries, 21 times in the chest and beat her with a metal rod before he jumped from the window of their western Sydney home.

Neither the 37-year-old nor her unborn fifth child survived the attack and Homann claimed to be mentally ill with ice addiction psychosis at the time of the murder.

At Friday's sentencing submission hearing, Ms Paepaerei's family said "only the devil" could have unleashed such violence on the "beautiful, smart, kind" Ms Paepaerei.

The victim's sister, Kylee D'Ugo described her anguish when she received a phone call on the morning of September 22, 2015, her birthday, informing her that her heavily pregnant sister was dead.

Reading a victim impact statement, Ms D'Ugo broke down in court.

"Not only was my sister gone but my (unborn) niece was gone as well," she said, reported the Daily Telegraph.

"The pain I feel, the emptiness I have inside ... will never go away."

Ms Paepaerei had been "outspoken with no filter" and Ms D'Ugo's best friend whose "infectious laugh" would brighten the day.

Addressing the murderer, Ms D'Ugo said she would never forgive him, "You have destroyed me and my family beyond repair".

Ms Paepaerei's mother Joyce D'Ugo described how her daughter had been excitedly expecting a daughter after having four sons.

She had already called the baby Mia, Fairfax News reported.

"You robbed us of seeing, holding and really knowing little Mia," Ms D'Ugo

Justice Lucy McCallum will hand down Homann's prison sentence on May 25.