The reason a Victorian man was doused with enamel thinner, set on fire and left to die by the woman who claimed to love him could forever remain unclear.

Kate Stone, 41, still denies unleashing “unbelievable terror and pain” on the father of her five children in December 2016.

The Bendigo woman maintained her innocence throughout a 22-day supreme court trial, after which a jury found her guilty of the “barbarous” killing of Darren Reid, her partner of decades. She will now spend at least 28 years in jail for murder.

On the day of his death, and with two of their young daughters at home, Stone doused her lover in the toluene and xylene mixture she kept in the shed, burning 95% of his body.

Engulfed in flames, Reid ran past his 16-year-old daughter and into the bathroom, telling her he was going to die.

Paramedics found him in the half-filled bathtub 30 minutes later. He remained conscious as his clothes – burnt into his skin – were cut from him and as he was wrapped in glad wrap.

Reid was then transferred to Bendigo base hospital, where he died the following day.

“His last conscious hours were of agony and passed in the belief he would die,” Justice Lesley Taylor said. “Your actions were despicable. For no obvious reason, you ended the life of the man you say you loved in an excruciating manner, making him suffer unimaginable pain.”

She added the reasons for the murder were “opaque”.

Reid’s mother told the trial her son had phoned her reverse-charges a month earlier, claiming Stone chased him down the street with a knife.

His stepmother told the jury that, on the afternoon of his death, Reid told her he wanted to leave Stone.

When interviewed by police, Stone said she loved Reid and there was never violence in their Long Gully home – although neighbours said they had heard yelling and fighting.

She lied to police, pinning the blame on three men she said threatened their family before one of them doused her partner in fuel and sparked it with a cigarette lighter.

Although the men were arrested on suspicion on murder, it later came to light one of them was in custody at the time and the other two were elsewhere.

Stone was jailed for 34 years and has already served 919 days in pre-sentence custody.