Tania Shailer and David William Haerewa have been sentenced to 17 years in prison for killing three year-old Moko Rangitoheriri.
Moko's family were at court, including his uncle Anthony Paki who told the court the heartache and sorrow had sometimes been too much to bear.
Moko's uncle thanks public for their support
He described waking at night still filled with anger.
"I hope that every day you are in prison that you feel the same.
"When you open your eyes every morning I hope that you feel the same helplessness, fear and pain that Moko had to endure at your hands."
Shailer and Haerewa were sentenced to a minimum period of nine years in prison in the High Court in Rotorua this morning. It is the highest sentence for the manslaughter of a child.
Justice Katz warned the packed public gallery to keep their emotions in check, despite their distress and pain.
The agreed summary of facts on the court file said Moko was subjected to months of abuse, leaving him with a ruptured bowel and head injury that killed him.
Crown prosecutor Amanda Gordon had asked for the maximum penalty for manslaughter - life in prison - to be imposed on Shailer.
In her summing up, Justice Katz said Moko was subject to extreme violence which was long and gratuitous and was witnessed by other children in the house.
She said there was evidence he had been smothered and his eyes were so swollen, he could barely see. He also had bruises and bite marks on his face.
Justice Katz said the violence committed by the couple was a "joint enterprise" and while it was likely Shailer committed the fatal stomping, Haerewa encouraged it.
The judge said both defendants tried to shift the blame, with Haerewa even blaming Moko for what had happened, and neither of them showed insight into their offending.
In her statement to court this morning, Moko's mother Nicola Dally-Paki described Shailer and Haerewa as "evil" and "monsters" for their psychological and physical abuse.
She said her world was changed forever when she was told her three-year-old son had been killed, and she would have changed places with her son and taken the abuse and torture happily to spare him.
Shailer was meant to be her friend and someone she could trust but instead had killed her son, Ms Dally-Paki said.
Shailer and Haerewa never told her they were having trouble coping, and they should have just given him back to her, she said.
Tania Shailer suffered depression, says lawyer
Shailer's lawyer Ron Mansfield said his client was suffering anxiety and depression and was under increased stress as she cared for six children - four of her own, as well as Moko and his sister.
Mr Mansfield said a report from a mental health expert found Shailer had lost control when dealing with Moko, who had behaviour issues.
The report said Shailer could not say if she carried out the fatal stomping but she did recall kicking Moko so hard he slammed into the hallway wall.
But Mr Mansfield said Shailer's rage was triggered by stress and she had hesitated taking Moko to hospital because she feared losing her children.
He said Shailer had the support of her family, but they were not in court because they feared being targeted.
Mr Mansfield said his client had pleaded guilty to save the children from giving evidence, and her early plea had also saved the community an enormous expense.
David Haerewa was 'less culpable'
The lawyer for Haerewa, Harry Edward, said his client was less culpable for Moko's death than his partner.
He said child witnesses reported seeing Shailer stomp on Moko, and she had also been seen biting him.
Mr Edwards said his client provided a dental mould which ruled him out of some of the bite marks on Moko's face and shoulder, and there was inconclusive evidence about who caused others.
Haerewa's previous convictions were for dishonesty, and he had expressed remorse for what had happened, Mr Edwards said.