Brett Walker had been hoodwinked into leaving work early and returning to his Sydney townhouse when he was ambushed and bashed by his "white witch" ex-wife.
Raquel Gaelle Hutchison feared her former husband was abusing children and exposing them to demonology, exorcism, ghost hunting and other paranormal activity, a court has heard.
She and her then-fiance, Paul Andrew Wilkinson, both 40, say they only intended to extract a confession when they let themselves into his home in October 2014.
But Mr Walker - who's been given a pseudonym - didn't survive their assault and Justice Peter Hamill found the pair guilty of manslaughter.
"The multiplicity of injuries show that this was a sustained and brutal assault," he said in the NSW Supreme Court on Friday .
The judge found them not guilty of murder.
There was no dispute at trial that Hutchison lured her ex-husband to his home by trickery, and he was attacked and significantly injured before dying of asphyxia and head trauma.
He was taken in the boot of a car to an isolated dirt road near Wisemans Ferry, where he was dumped by his ex-wife and Wilkinson.
Hutchison admitted to the assault but claimed Mr Walker was still alive when they left him by the road - something Justice Hamill rejected in his Friday verdict.
She pleaded not guilty to murder due to mental illness and said she had no intention to seriously injure or kill her former husband but wanted a confession she could take to authorities.
Justice Hamill, who identified Hutchison as the major aggressor in the assault, found her child abuse concerns were real - regardless of whether any abuse actually occurred.
The judge, who made no finding on whether there was abuse, noted Hutchison's ex-husband was supported and remembered by a loving family.
He had no doubt Mr Walker had exposed children to strange things "due to his interest in esoteric paranormal activities".
However, there was also evidence Hutchison considered herself a Pagan or white witch and that she and a child had written spells and made a voodoo doll of her ex-husband.
Justice Hamill found Hutchison and Wilkinson didn't go to the victim's house with an intention to cause serious injury, but she "lost control of herself" in her fury and anger.
That loss of control was linked to her psychiatric conditions, the judge said, and the Crown hadn't eliminated the possibility she believed her conduct was necessary for the protection of children.
However, he was still satisfied that her and Wilkinson's actions weren't a reasonable response to the situation even as they saw it.
Hutchison will next face court on November 19, while Wilkinson is not due back until next year.
Australian Associated Press