Stephen Wilde, 65, brandished a carving knife at the woman in their home near Shrewsbury and told her "you're not going anywhere. Don't ever believe I won't kill you," Shrewsbury Crown Court heard on Friday.
The marriage was ending and the victim was making preparations to leave Wilde when he confronted her at the home in September of 2019.
Prosecutor Miss Olivia Appleby told the court that by September 8 it was "quite clear that the relationship between husband and wife had broken down irreparably".
"The defendant was well aware she was leaving him," said Miss Appleby.
They began arguing about a chequebook relating to a joint business and Wilde said: "You better make sure there are good locks on the doors [in the new home]. Sleep with one eye open."
He also referenced the cancer she was suffering from and said he wanted to kill before the illness did. He said he hated her and wanted to "do it [himself]", the court heard.
The victim began recording the encounter on her phone after Wilde picked up a knife. The short clip was played to the court and the woman could be heard saying: "I don't want you to kill me. Let me go now please, let me out of the house please."
Wilde can also be heard saying: "You're not going anywhere. Don't ever believe I won't kill you."
The court heard that he put the knife to her throat and tilted her chin upwards to expose her neck to the blade. The victim was eventually able to escape through the patio.
In victim impact statements she described taking time off work with stress and avoiding areas like Shrewsbury and Barmouth, where she might normally socialise, for fear of the defendant seeing her. The couple have now divorced.
For Wilde, Mr Kevin Jones acknowledged his behaviour was "terrible" but said that he had previously been of good character and had not committed any crimes since.
Judge Anthony Lowe told the defendant: "There really can be no excuse for what you did.
"What really makes this serious is the use of the knife."
He imposed a sentence of 15 months and suspended it for two years, but said that if not for his advanced age and his good character there would have been "no justification" for suspending it.
Wilde, of Holyhead Road in Nesscliffe, will also have to pay prosecution costs of £1,417 and observe a curfew for three months.
The judge also imposed a restraining order banning him from contacting or going near his victim.