A devoted mother was a "shattered mess" who quoted conspiracy theories the day before she killed her two boys, a Supreme Court jury has been told.
Donna Fitchett, now 48, suggested the Howard Government put Martin Bryant up to the Port Arthur killings, and that a BHP employee murdered former Prime Minister Harold Holt, according to her sister Louise Mitchell.
The next day, September 6, 2005, she gave her sons a "cocktail" of drugs, suffocated or strangled them at their North Balwyn home, and was found by her husband in a darkened house in her bra and underpants.
Ms Mitchell and David Fitchett, the father of the dead boys, were among the witnesses who yesterday described the events surrounding the killings, which took place two days after Father's Day.
Standing in the witness box, Mr Fitchett cried as he read from a letter - in his wife's handwriting - found at the Dight Avenue house on September 6.
He bowed his head as a tape recording of his telephone call to emergency services was played before the jury and Justice Geoffrey Nettle.
In the call, Mr Fitchett told the operator he believed his wife had killed their children, and had overdosed.
He said he tried to revive his older son, Thomas, 11, but discovered both he and younger brother Matthew, 9, were stiff from rigor mortis.
In the background, Donna Fitchett was recorded as saying : "I don't want to live". At one point, David Fitchett said: "She just f...ing slashed her wrist".
Donna Fitchett has pleaded not guilty to murdering the couple's sons.
Prosecutor Gavin Silbert, SC, has alleged the boys were murdered in a pre-meditated, cold-blooded killing.
Defence counsel Graham Thomas, SC, has said psychiatric evidence was expected to show Donna Fitchett was mentally impaired at the time.
Yesterday, Mr Fitchett struggled to read from the letter - addressed to him- that outlined the killings. Donna Fitchett said she overdosed Thomas and Matthew, then "suffocated (and) strangled them".
"They were happy this morning, and said they loved you, and had a great Father's Day," she said.
"I pray I do not live through this. I've said some angry things, but I truly forgive you. I hope you find the strength to go on without us...I just couldn't abandon our beautiful boys. I've been dead for a few days and I just wanted peace."
During cross-examination, he told Mr Thomas that in the days before the killing, Donna Fitchett said he was not capable of caring for the children.
She said she had been seeing a psychologist, and had come to the conclusion that he was a "passive aggressive" person and she was not going to live with him any more.
Ms Mitchell said in court that everyone, according to Donna Fitchett, seemed to be passive aggressive, or have a label. She said Fitchett thought her psychologist, Patra Antonis, was her second mother and best friend.
"I said: 'Your best friends don't charge you to see them every Monday', and I believe she changed when she started seeing this woman, and I couldn't talk to her any more," Ms Mitchell added.
Ms Antonis said she saw Fitchett 37 times, initially after she (Fitchett) reported marital difficulties. She agreed she told police immediately after the killings that Fitchett had chronic depression. She said Fitchett had reported to her that she had post-natal depression with each child.
The trial continues.