Peter Stalgis, 60, killed 55-year-old Angel Conoby at their home in Berkeley Mount, Harehills, in May.
He denied murder but was convicted by a Leeds Crown Court jury after a trial.
The jury was told Stalgis had kept financial problems secret and that the couple of 33-years were on the verge of being evicted from their home.
Reading a victim personal statement to the court, Angela Conoby's sister Michaela, told Stalgis she wanted him to look at her as she spoke.
Michaela Conoby said: "No-one has the right to take any person's life, but the violent and vicious way that you killed my sister makes it even harder."
She added: "I feel angry and empty. I feel like my heart has been ripped out.
"I have lived through a lot of very difficult things, but I have never ever felt this devastated and this level of grief in my life.
"I hate you for making me feel this way, you had no right to leave me without a sister."
Michaela Conoby said her sister was a "generous, kind, unassuming lady."
Stalgis had told the court he could not remember carrying out the fatal attack or why he would want to hurt Ms Conoby.
Mitigating, Abdul Iqbal, said "He does feel tormented. This is not a man without remorse. He has never feigned the emotions he has shown throughout this trial.
"Whatever occurred that day was hugely unexpected and hugely out of character."
Jailing Stalgis for life with a minimum 14-year term, Judge Tom Bayliss QC said he was satisfied that Stalgis killed Ms Conoby in a brutal knife attack two weeks before her badly
decomposing body was found in the house on May 20.
Judge Bayliss said: "Those who knew you described you as a happy and devoted couple. There is no suggestion of a history of domestic abuse here."
Judge Bayliss added: "You picked up a knife in the kitchen and took it into the sitting room and carried out the attack,
"You left Angela Conoby bleeding and dying on the floor of her own home and you did nothing."
And Judge Bayliss told Stalgis: "You showed nothing but love and devotion to Angela Conoby...I'm quite satisfied this offence was entirely out of character.
"The death of Angela Conoby was indeed a tragedy. A tragic end to what had been a devoted and loving relationship.
"But it is I'm afraid Peter Stalgis, a tragedy entirely of your own making."
The jury was told a police officer forced open the door to the property on May 20 after the victim's sister, Michaela, contacted police worried for her safety.
Footage from the officer's body camera was shown during the trial and Stalgis could be heard repeatedly saying "I lost the house", "she didn't know" and "I'm sorry".
At the police station Stalgis confided that he had "done a really bad thing" and asked for forgiveness "for killing the woman he loved".
Officers also discovered he had cuts to his left wrist that may have indicated a suicide attempt.
Later, when he was formally interviewed, he made no comment to the police's questions.
At the house, police found a pile of letters from solicitors and an apparent suicide note written by Stalgis which was addressed to Ms Conoby's sister and her partner.
The letter, read out in court, stated: "I lost the house and I killed the love of my life. I cannot live with the shame, please forgive me if you can. I deserve to rot in hell. As my friends and
family I'm so, so sorry to put you all through this. I love you."
Detective Chief Inspector Ian Scott, of West Yorkshire Police Homicide and Major Enquiry Team, said after the sentencing hearing: “The murder of Angela Conoby at the hands of her
long-term partner Peter Stalgis was an absolute tragedy.
“It was completely unnecessary and it appears only he will ever really know what led him to violently end the life of the woman he claimed to love.
“Angela’s family have been left completely devastated at her death in these circumstances, and we hope it will help them in some small way to know that Stalgis has now had to answer for his actions.”