Aaron Swift stabbed Nick Williams more than 70 times to the head, neck and body in the living room of his home in Wakefield.
Swift had been having an affair with Mr Williams’s partner Elizabeth Carrigan and carried out the killing after she ended the secret relationship.
Swift was jailed for nine and a half years at Leeds Crown Court today. He was found not guilty of murder but had pleaded guilty to manslaughter on the grounds of loss of control.
Days before the killing, which took place on December 16 last year, Miss Carrigan, 24, had told Swift she could not see him any more as she planned to start a family with Mr Williams, 26.
Swift then went on to the internet to find the address on Bottom Boat Road, Stanley, Wakefield, where the couple lived.
The 33-year-old drove from his home in Rotherham and parked close to the house before going to tell Mr Williams that he had been seeing Miss Carrigan behind his back.
The two men had never met each other prior to the incident.
CCTV footage showed Swift approaching the property and knocking on the door before being allowed inside.
Jonathan Sharp, prosecuting, told a jury how Swift carried out the attack soon after entering the house.
Mr Sharp said: “Aaron Swift had the advantage of surprise. He inflicted no fewer than 72 wounds to Nick. Most of them were to his neck.
“Those wounds cut in to his jugular vein. He bled profusely.”
The jury saw photographs of the living room taken after the attack which showed blood on the walls. The furniture and Christmas tree had also been overturned during the struggle.
Swift took Mr Williams’s mobile phone and moved the landline phone so he could not call for help. He left the house around 40 minutes later and walked back to his car via a secluded footpath to avoid being seen by anyone as he was covered in blood.
After the killing Swift continued to send text messages to Miss Carrigan from his own phone as if nothing had happened. He also rang her to talk about his plans to go to a Christmas party.
Miss Carrigan found her partner’s body the next morning when she returned home from work.
The court heard Miss Carrigan, a support worker for adults with learning difficulties, and Mr Williams, a welder, had been together for four years. They had recently made the decision to have a child together.
The day before the incident she had been to a clinic to have her contraceptive implant removed.
The jury heard Miss Carrigan sent a text message to Swift soon after emergency services had arrived at the property to deal with the incident.
Giving evidence during the trial, Miss Carrigan said: “I was in absolute shock and could not think straight. When Aaron rang me it was a quick conversation and he was stuttering on the phone, telling me to go to my family and that I needed my dad and that he would contact me later.”
The court heard Swift destroyed his own mobile phone a day later and bought a new one in a bid to conceal his relationship with Miss Carrigan.
He then tried to arrange an alibi when it became clear that police would want to talk to him.
Days before the killing Swift had also asked a work colleague: “If somebody did something really really bad they had got a reason to do it, could you forgive me?”
He claimed he had initially acted in self defence after Mr Williams attacked him when he went to speak to him about having the affair with Miss Carrigan.
Mr Justice Edis told Swift he had acted with “calculated dishonesty”.
He said: “In truth you are so self obsessed that nothing mattered to you last December but to break the bond of your victim and his partner.
“This was a killing done with intent to kill and with savagery. It was done in fear but also in anger caused by sexual possessiveness.
“The circumstances in which violence began was arranged by you and not the victim. It is therefore a very serious cause of manslaughter.
“You knew at all times what you did was not reasonable self defence.”
A victim statement was read out in court on behalf of Mr Williams’s mother, Kathleen Hurst, in which she said: “I have been asked to try and put in to word the loss of my son. I can say I am totally heartbroken. My world has collapsed. I feel I have lost a part of of me that will never return.
“Why someone would want to take Nick away from me I do not know.”
“He was planning to start a family with Lizzie, his girlfriend. I was looking forward to becoming a grandmother.
“Nick had so much to look forward to.”
After the case, Detective Inspector Andrew Welbourn of the Homicide and Major Enquiry Team, said: “We welcome the sentencing of Aaron Swift today for the brutal crime which resulted in the death of a well-liked and decent man.
“Swift carried out a truly ferocious assault, inflicting multiple stab wounds from which Nicholas had virtually no chance of survival.
“He then ransacked the victim’s shared property to try and disguise the nature of his assault.
“Police received a strong response to our appeals in the immediate aftermath of Nicholas’ death and I want to thank everyone who contacted officers.
“Our thoughts remain with everyone affected by Nicholas’ tragic and untimely death.”