Gary Brown was ordered to serve at least 27 years in prison before he can apply for release after stabbing Alyson Watt 42 times in the fatal attack at her home.
The dying victim managed to reveal to a neighbour who went to her aid that Brown was responsible for the merciless attack on her.
Brown, 55, also carried out a vicious hammer attack on a 16-year-old boy at Ms Watt’s home leaving him with serious head injuries and in need of long term care.
A judge told Brown at the High Court in Edinburgh: “Your behaviour was murderous and unforgivable.”
Lord Summers said that Ms Watt had died at the scene and Brown had sentenced the boy, who was left profoundly disabled and barely able to communicate, “to a living death”.
The judge said that victim impact statements he had been provided from relatives of the deceased made “harrowing reading”.
The court earlier heard that former Falklands war veteran claimed that he immediately “fell in love” with charity worker Ms Watt, 52, after they met up through a dating website.
He thought the Barnardo’s worker was “interesting and attractive” but months before the murder found a text on her phone which implied she may have kissed another man which became an obsession.
The Scottish Power engineer revealed to a workmate that he had read messages on a phone and asked him what he thought of “a drunken kiss”.
Brown, formerly of Uddingston, in South Lanarkshire, turned up at Ms Watt’s home in Paisley, in Renfrewshire, on June 2 last year and repeatedly knifed her.
Two of the wounds he inflicted on her damaged jugular veins resulting in rapid and profuse blood loss and death.
A neighbour, Peter Harris, 71, who went to the aid of the victim said she revealed that Brown was the perpetrator of the vicious, fatal attack.
Mr Harris said: “Her hand was dragging down the window. I could see the blood running down.”
“I took to my heels once I saw her. I ran straight to Alyson – into the kitchen at the back door,” he said.
“She was lying on the floor and was in a bad condition. There were wounds to her face and neck, blood was pulsing out,” he said.
“I asked was it Gary that did it. She whispered ‘yeah’. She tried to nod but could not move her head properly,” said Mr Harris. He added that the teenage boy was also in “a bad way”.
After committing the attacks former Scots Guardsman Brown drove to the south-west of Scotland and claimed he intended to take his own life, but was arrested by police.
Brown earlier stood trial after denying the murder of Ms Watt, claiming that he was suffering from an abnormality of mind at the time of the offence.
But a jury rejected a plea to convict him of the lesser offence of culpable homicide. He admitted attempting to murder the 16-year-old.
Defence counsel Brian McConnachie QC said that Brown suffered from a borderline personality disorder.
He added: “There has never been any dispute about who was responsible for these crimes.”
Mr McConnachie said that Brown’s service in the Falklands was a period when he effectively thought his life would come to an end.
The defence counsel said it was accepted that by the time Brown became eligible for release from prison for the offences he would be “frankly a very old man”.
Ms Watt’s former partner, Graeme Scott, was present to see Brown being sentenced and said: “Justice has been served as far as I am concerned.”
Mr Scott said he believed that Ms Watt saved the boy in the house who was attacked by Brown. He said: “It has been a massive impact on a lot of people, Alyson’s friends, Alyson’s family. It has had a devastating effect.”