Chris Dawson, a former teacher from Sydney, was sentenced to spend up to 24 years in prison for killing his first wife, Lyn, in 1982.
Her body has never been found.
The Crown argued that he killed his wife to have an affair with their teenage babysitter, who he later married.
In his sentencing, Justice Ian Harrison said that the murder was a serious crime.
He also noted that Lyn was no longer capable of defending herself.
The judge said that Dawson’s actions were motivated by his uncontrollable desire to be with another woman, known as “JC”.
The prospect of losing his wife made him want to kill her.
The judge found that the lack of a body recovered from the area where Lyn was killed was an aggravating factor in the case.
He sentenced Dawson to a maximum of 24 years in prison.
He will be eligible for parole in 2040.