Adrian Prout strangled his wife Kate in the shooting lodge at their Redmarley farm, then sat down to a glass of whisky.
Prout, who is serving a life sentence for her murder, "snapped" after an argument in which she promised to humiliate him, a coroner heard yesterday.
At the inquest into the former teacher's death, Detective Inspector Steve Bean, of Gloucestershire CID said on November 5, 2007, Prout went out to the lodge at Redhill Farm to prepare for the following day's shoot.
"She followed him and they began arguing," Mr Bean said.
"She was planning to humiliate him in some way the following day. He snapped, and thrust his right hand into her neck and squeezed for 10 to 15 seconds. She didn't struggle. She fell backwards."
He told Assistant Deputy Coroner Katie Skerrett that Prout fixed himself a glass of whisky, before wrapping Kate's body in a curtain, putting it in the back of his Land Rover and went to the pub. When he returned, he drove to a pheasant pen and dug a hole with a shovel and buried her body.
The coroner read out a doctor's post mortem report which found fractures to her thyroid were consistent with strangulation.
Mrs Skerrett concluded: "I have no hesitation whatsoever in recording an unlawful killing verdict in this case."
After the inquest, in a statement read outside the court, Kate's brother Richard Wakefield said: "This is another sad day for the family and being here today has enabled us to hear more about Kate's death. In January we held a private cremation where we were able to say goodbye and we know now she is at peace.
"Kate will always be in our thoughts and is deeply missed."
And Mr Bean told The Citizen: "When Adrian Prout took us to the farm, he was definitely very remorseful and did apologise to the friends and family of Kate telling them he should have said from the start what he did."
He added: "Adrian Prout deceived a lot of people and the implications are massive. "
Police officers discovered her body in November after Prout sensationally confessed after failing a lie detector test. He was convicted of her murder in February 2010.
