A former Ukip councillor who murdered his wife months after he had an affair with their son's partner is facing a life prison sentence.
Ex-Royal Marine Stephen Searle, 64, claimed he had been defending himself after his 62-year-old wife Anne Searle attacked him with a knife, but jurors at Ipswich Crown Court took three-and-a-half hours to find him guilty of her murder.
Mr Justice Green said Searle's "act of infidelity in one way or another led to this".
Prosecutor Andrew Jackson said Searle had probably placed his wife in a choke hold that he had knowledge of from his military training.
Searle showed no reaction as the verdict was read out on Tuesday following a six-day trial.
Mr Jackson told the trial that the Searles' marriage had been under strain since Mrs Searle discovered her husband's affair with their son Gary's partner Anastasia Pomiateeva, who was mother to at least one of their grandchildren.
This was discovered around June 2017, he added.
In a 999 call made on December 30 last year and played to jurors, Searle told police: "I've just killed my wife."
Officers attended their home in Stowmarket, Suffolk, within minutes of the call made at 10.19pm and found Mrs Searle dead.
"The prosecution case is that on that Saturday night there had probably been yet another row between the two of them and in anger the defendant strangled his wife to death," Mr Jackson said.
A post-mortem examination recorded that Mrs Searle died of compression of the neck.
Forensic pathologist Dr Benjamin Swift said Mrs Searle would have lost consciousness after about eight to 15 seconds of pressure being applied to her neck, and death required further sustained pressure for a period of minutes.
Searle had been married to his wife for 45 years and they had three sons together.
In a victim impact statement, one of Searle's sons, also called Stephen Searle, said: "Not only have I lost my mum, but because of what he's done I've lost my dad too."
Searle is to be sentenced at Ipswich Crown Court on Wednesday.