Sara Ege, 33, denies beating Yaseen Ali Ege to death and setting fire to his body.
Mr Ege said he had "no idea" why his wife would say he beat her.
Mr Ege denies a charge of causing the boy's death by failing to protect him.
Earlier on Monday, Mr Ege cried as the court was shown a video of his son.
Sara Ege denies beating Yaseen Ali Ege to death and setting fire to his body.
Yaseen's father Yousef Ege, 38, denies causing his death by failing to protect him.
Det Ch Insp Crisp praised the "dignity and restraint" shown by Mrs Ege's family throughout the proceedings.
At the time of her murder, Mrs Ege's family said she was a gifted and talented teacher.
It followed a domestic incident in which Mrs Ege suffered a split lip, the court has heard.
"Sara Ege made no attempt to seek the medical attention he so obviously needed, " prosecutor Ian Murphy said.
He thought it meant Mr Ege had told his wife that Yaseen was with Allah now, the court heard.
BBC: Yaseen Ali Ege death: Father Yousuf Ege 'unusually calm'
Police officer Andrew Williams described the moment Mr Ege was told by a doctor that his son was dead.
BBC: Yaseen Ali Ege death: Father Yousuf Ege 'unusually calm'
Mrs Ege, of Pontcanna, Cardiff, later retracted the confession made to the police over several days in July 2010.
Mr Ege was arrested but never charged because, Mrs Ege has told the court, she refused to press charges.
In a statement he said Sara Ege was clearly suffering from smoke inhalation.
BBC: Yaseen Ali Ege death: Father Yousuf Ege 'unusually calm'
Barach Bandavad, of Highbury Road, Horfield, was convicted of murdering Judith Ege, 58, and was sentenced to a life term.
He said Mr Ege fell to his knees with a loud bang and started crying, calling out his son's name.
BBC: Yaseen Ali Ege death: Father Yousuf Ege 'unusually calm'
Mr Ege told the policeman he did not want to tell his wife, because he thought she was too weak.
BBC: Yaseen Ali Ege death: Father Yousuf Ege 'unusually calm'
Mrs Ege made a confession to police within days of Yaseen's death at their home in Cardiff in July 2010.
The court heard Ege become more and more frustrated with her son's inability to learn the passages he needed to.
Mrs Ege had visited Bandavad's house with her husband to retrieve items belonging to his daughter, who had previously dated Bandavad.
Giving evidence in her defence, she said Mr Ege had been violent towards her right from the start of their marriage.
Mrs Ege is accused of hitting and punching Yaseen and punishing him using a hammer, a rolling pin and a slipper.
Jailing Ege on Monday, the judge said Yaseen had suffered prolonged cruelty.
After the sentencing, Yaseen's father, Yousuf Ege, paid tribute to his son.
BBC: Sara Ege: Life jail for son's murder over Koran studies
"On 30 June last year, Judith Ege went to Bandavad's address in Horfield to retrieve her stepdaughter's belongings, " Det Ch Insp Crisp added.
Mrs Ahmed also spoke of being threatened by the Ege family in India after Mr Ege was arrested for assaulting his wife in 2007.
The jury heard how Mr and Mrs Ege were taken to hospital in a separate ambulance to their son, who was pronounced dead en route.
BBC: Yaseen Ali Ege death: Father Yousuf Ege 'unusually calm'
Mrs Ege said in interview that Yaseen had collapsed in a similar way about six weeks earlier and had been fine after a night's sleep.
Earlier Maura McGowan, QC, for Mr Ege, had questioned him about how he had come to learn of the real reason for his son's death.
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