An ex-Royal Marine accused of strangling his wife to death told a court he put one hand on her neck while he took a knife from her and went for a cigarette after she stopped moving.
Former UKIP councillor Stephen Searle, 64, denies murdering his 62-year-old wife Anne Searle at their home in Stowmarket, Suffolk on December 30 2017.
He told jurors at Ipswich Crown Court that she stabbed a knife into the sofa earlier that evening and later attacked him with a knife as he was leaving the downstairs toilet.
He said they fell to the floor as he tried to disarm her.
"My right hand was on her neck and I was more concentrating on my left, it was very difficult to hold her down," Searle said.
"It was one-handed, open-handed as far as I can remember.
"I wasn't concentrating on that part of her body. I was concentrating on the threat."
He continued: "Eventually she stopped struggling and I went thank f*** for that and said 'I'm going to have a fag' and went through to the conservatory."
His barrister Steven Dyble asked if she replied, to which he answered: "No".
Asked if he thought his wife would come into the conservatory, Searle said: "I was expecting it to kick off again, yeah."
He said he "just sank" when he found her lifeless later that evening.
"It just didn't make sense," he said. "I was calling her name, it just didn't make sense."
Asked if he considered calling an ambulance, he told the court: "No, and I don't know why.
"I didn't even think about calling anybody, I just sat there like a bloody idiot."
He said he later called police.
Searle denied that they argued that night about his affair with his son Gary's partner Anastasia Pomiateeva, who is mother to one of his grandchildren.
He said his wife discovered his infidelity in August 2017, he ended the affair and they continued living together.
They had been married for 45 years and had three sons together.
Searle said both he and his wife would drink "huge amounts", with him drinking eight to 10 cans of lager daily and his wife getting through a 1.5 litre bottle of gin in two days.
Asked if he intended to kill his wife, he replied: "No." Asked if he intended to cause her serious harm, he also answered: "No."
Prosecutor Andrew Jackson put it to Searle that his wife removed her wedding ring as a "signal that the marriage was over" that night.
Searle replied: "No sir, she did not remove her wedding ring because the marriage was over."
The trial continues.