Hancock had already pleaded guilty to murdering his 39-year-old former spouse, from Duffield, and Martin Griffiths, 48, from Derby.
Nobody else was in the house at the time as the couple’s three children had been staying with a grandparent at the time of the killings.
DerbyshireLive reports Hancock had been to a pub near his home before returning with two women.
After they left, he went upstairs and woke his sleeping mother to tell her he knew Martin was at the former marital home.
Prosecuting barrister Michael Auty QC said: “The defendant had two knives in his hand, one was an 18cm chef’s knife and the other was longer, around 32cm.
He said to his mother ‘I feel like I want to kill them’. He told his mother he loved her and told her he would be sent away for 25 years. She said she had never seen him so calm.”
Horrified, his mother, Denise Hancock, called 999 and said her son was heading over to the Duffield home armed with two knives.
The prosecutor said 15 minutes later Hancock called 999 himself and told the operator: “I have just murdered my wife in her bed. I have stabbed them. There is blood everywhere.”
Forensic pathologist Dr Stuart Hamilton described the scene of the murder as a bloodbath and the most violent attack he had ever seen.
In his police interview, Hancock described how he inflicted the fatal injuries, telling officers: “I’ve clearly done it, haven’t I? I have blood all over my clothes and it is clearly theirs. I have just lost it, haven’t I?”
Mitigating, the killer’s barrister Clive Stockwell QC said: “Your honour will impose a life sentence on Rhys Hancock and it is entirely justified.
“The impact of his criminality did not just take the lives of Helen and Martin but has damaged the lives of many other individuals. He is very alive to that fact.
Sentencing, Judge Nirmal Shant QC said: “What you did that night deprived two families of the people they loved. You made a decision to kill not just your wife but her companion. You told your mother it was you or them.
“You made your way to Helen Hancock’s home and that was a home she was entitled to feel safe in. You attacked them and it was a brutal attack and led to their deaths.
“It was described by those who visited the scene as a bloodbath. You intended to kill them before you left your mother’s house.
“You armed yourself with two knives, both formidable weapons.
“It is clear you had an intent to kill. They were in bed defenceless.”
Hancock, of Portland Street, Etwall, is a former headteacher at Stanton Vale School, in Long Eaton, Derbyshire.
Helen had been working as a PE teacher at Fountains High School in Burton-on-Trent, Staffordshire.
Her family had previously described as a “lovely, beautiful, friendly, bubbly and social person”.
Martin was said to be “a lovely dad, husband, son, brother and uncle who had a passion for adventure, running and a love of animals”.