Milorad Zaric, 48, fatally attacked Vicki Apostolopoulos and assaulted her son after chasing his own fearful son into his neighbour's property in eastern Melbourne.
Ms Apostolopoulos's family sat in a packed courtroom, wiping away tears throughout Zaric's sentencing in the Victorian Supreme Court on Wednesday.
Justice Jacinta Forbes said the November 2024 attack was serious and his actions took a life and irrevocably changed many others, as evidenced in the 24 victim impact statements from family, friends, neighbours and colleagues.
"This reflected the breadth of love Ms Apostolopoulos brought and the loss occasioned by her death," she said.
But Justice Forbes took into consideration Zaric's reduced moral culpability due to his ketamine-induced psychosis, deep remorse, previous good character and early guilty pleas as reasons for her to set a sentence below the standard 25 years.
She set a head sentence of 21 years and five months and a non-parole period of 14 years and six months.
Zaric, 48, had been chasing his teenage son on the morning of November 16 after abusing ketamine, cannabis and alcohol the day before.
After the father punched his son, pushed the boy down the stairs and stomped on his head, the then-15-year-old boy sought refuge in Ms Apostolopoulos's home next door.
The confused neighbour let the boy inside and shut the door again.
When Zaric wouldn't stop banging on it, she opened it and heard her killer chillingly utter: "Welcome home, Vicki."
Zaric then retrieved a knife from his waistband and plunged it into her neck, stomach and shoulder in a frenzied attack.
The Bayswater woman's own son, aged 16, grabbed Zaric in a chokehold and ordered his 12-year-old brother out of the house.
Zaric repeatedly punched the teen and slammed him against a wall, but the boy only let go to run to safety.
"You attacked a woman who had no reason to fear you," Justice Forbes said.
The victim opened her door to Zaric in a sign of friendship, the judge said.
"You stabbed her with no reason, without explanation or warning," she said.
When police arrived, he told them he had taken ketamine before growling and calling out for Satan.
Two days before the murder, Zaric had texted to thank her and praised her "amazing" cupcakes, which she had baked and taken to his house.
Defence barrister Ruth Shann SC had argued the killer's crime was out of character and his mind was altered by ketamine.
Ms Apostolopoulos's sister Mary Kadis previously said his drug-addled state was no excuse, and that he was able to make choices that day, unlike her sister.
Their mother, Sofia Apostolopoulos, said the grief she carried following her daughter's death was beyond words and likened it to being trapped in a living nightmare.
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