David Paterson, 81, had made peace with God, had said goodbye to some of his relatives and was waiting to die from cancer with dignity - probably within days - when he was killed by a woman he knew.
Heather Davidson, 53, from Sowerby, Thirsk, North Yorkshire, cried in the dock of Teesside Crown Court when she replied in a shaky voice “guilty” to the charge of murder.
The basis of plea was not revealed in court, but it was understood she will claim it was a mercy killing.
She knew Mr Paterson, a loving family man with deeply-held religious beliefs, through church.
And it emerged after the hearing that she called the cancer charity Macmillan before she killed the widower. It was unclear how much detail she went into while on the phone to the charity.
Two phone calls she made prior to committing murder will be played at the sentencing hearing on June 5.
Davidson, with black glasses, her brown bob-length hair swept off her face and wearing a white sports top with the collar up, dabbed her eyes with a tissue during the hearing.
Jonathan Sharp, prosecuting, said there was a difference between the Crown’s case and the defence’s with regard to the basis of plea and the term “mercy killing”. He said it would not make a difference to the sentence.
It was understood that under relatively new legislation only certain people with a close-relationship to the dying person can use the claim of mercy killing in their defence.
Judge Simon Bourne-Arton adjourned sentence to allow for reports to be prepared.
He told the defendant she had the “good sense” to admit the charge and that she will receive credit for the guilty plea.
She will face a life sentence but the judge said the minimum term she must serve in jail had yet to be determined. He remanded her in custody.
After his death at Sowerby House care home on February 11, relatives said: “David lived in the Thirsk area all of his life and previously worked as a welder at Thircon in Thirsk for 30 years.
“He was a devoted family man who adored his nieces and nephews.
“He was devoted to his wife and cared for her when she became ill, up until her death in March 2014.
“They were a very private couple who idolised their family and enjoyed being a part of their local community.
“David enjoyed writing poetry and had some of his poems published.
“He was a champion leek grower and also enjoyed quizzes and board games, anything that challenged his mind.
“He was an active member of his local church and enjoyed bowling until his health deteriorated and he was no longer fit enough.
“We will remember David as a devoted husband and family man who enjoyed the simple pleasures in life.”
The family released a photo of Mr Paterson which they thought dated back to the 1980s.
The care home, in a large Edwardian house on an attractive road in the quiet village of Sowerby, is privately-run.