Marcus Osborne murdered Katie Higton, 27, and Steven Harnett, 25, in May last year.

He forced his way into the home he used to share with Ms Higton in Huddersfield and attacked her as she returned from a date at a cinema.

Prosecutors said she put up a "courageous struggle" but suffered 99 knife wounds, including more than 20 to the face.

Osborne, 35, then used her phone to lure Mr Harnett to the house, stabbing him 24 times and leaving him with mutilated genitals.

He also raped another woman who was at the house and held her at knifepoint overnight.

Leeds Crown Court heard four children were in the property at the time, and that after the killings he said: "Romeo and Juliet can die together now."

He also invited neighbours to come to see the bodies, said Sky correspondent Frazer Maude.

As he was led away on Friday, a family member shouted: "I hope you rot in hell", while a statement by Ms Higton's mother called Osborne a "monster of the worst kind".

He now joins a list of Britain's worst killers, such as Rose West and Milly Dowler's killer Levi Bellfield, who will never be released.

The murders happened soon after Ms Higton ended her five-year relationship with Osborne following a domestic violence incident in late April.

'Motivated by sex'

Ms Higton visited the police station on 10 May and told officers he regularly attacked her and was controlling and coercive.

She told police that Osborne had threatened to "slit her throat if she said what he had done" and that "if she ever got a boyfriend he would kill them both".

He was arrested two days later on suspicion of domestic violence but released on bail and told not to return to the house or contact Ms Higton.

He then spied on her before carrying out the killings on 15 May.

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Osborne, who also has convictions for violent offences against two previous partners in 2011 and 2012, pleaded guilty to the murders as well as the rape.

The court heard he had found out about Ms Higton's developing relationship with Mr Harnett by hacking into her Snapchat account.

Judge Mrs Justice Lambert said there were no mitigating factors.

"This is a case of such exceptional seriousness that even a very long minimum term would not be a just punishment. What you did that night was horrific," she told Osborne.

She said the killings were driven by "pathological jealousy".

"Everything you did was motivated by sex and your need to sexually humiliate and degrade," the judge added.

Osborne also received a 10-year concurrent sentence for the rape and false imprisonment of the other woman in the house.

Speaking after the sentencing, Mr Harnett's family said police are failing to protect the most vulnerable, particularly when it comes to acting on domestic abuse reports.

His brother, Jordan Harnett, said: "How does a man with a history of domestic violence walk free from a police station on bail?

"Police are unable to protect people who need it the most. What are our government doing?"

"I want police to take threats to kill more seriously. Police need to do more. I'd like to see the police listen to women like Katie."

West Yorkshire Police said the murders were "truly dreadful".

However, it said it was limited in what it could say as an investigation into its handling of the case - in conjunction with police watchdog the Independent Office for Police Conduct (IOPC) - is ongoing.