Brisbane fashion designer Katie Anne Castel killed her husband by throwing a knife into his heart during an argument over him coming home late.
The knife lodged in Jarred Castel's chest, piercing his heart, five days before Christmas in 2017.
He pulled it out, but the four-centimetre wound proved fatal.
Castel was given a nine-year jail term following her 2019 trial, but appealed the sentence in Queensland's Court of Appeal on Monday, saying it is excessive.
Jarred Castel's father Tony says she is simply manipulating people to get out of prison earlier.
"All of it is to manipulate to reduce her sentence. It's all about her," he said outside the court.
Mr Castel said the couple's son, who was four when his father died, would take years to get over the trauma.
He would be an "orphan" in foster care if it wasn't for family.
"I can't bring Jarred back ... but I've got to try and protect the son because he's scared of her," he said.
Crown prosecutor Dzenita Balic says Castel's actions were described by the trial court judge as deliberate and dangerous.
"She was not provoked .. was not acting in self-defence and ... was not the victim of domestic violence," Ms Balic said.
In sentencing Castel last year, the judge said a letter written by Castel showed she failed to comprehend the hurt she had caused.
"The letter, to me, has ... inappropriate details about concerns for your own plight and inappropriately expresses tones of religious superiority about being in some sort of state of grace," Justice Jean Dalton said.
The appeal court decision has been reserved.