Ambulance technician and bouncer Jonathan Vass, 30, launched a frenzied knife attack on nurse and mother-of-one Jane Clough, 26, as she arrived for work at Blackpool Victoria Hospital in July.
She was admitted to the hospital's accident and emergency unit where she worked as colleagues tried in vain to save her.
Vass, described as "manipulative and controlling", was freed to kill after being given bail while awaiting trial over allegations that he had repeatedly raped her. The rape charges were dropped after the murder.
John and Penny Clough, her parents, were angered by both decisions - first to free him and then to let the rape charges lie on file.
They sat in the public gallery just yards from Vass in the dock as he was jailed for life at Preston Crown Court after pleading guilty to murder at an earlier hearing.
Judge Anthony Russell QC handed down the mandatory life sentence before telling Vass he will serve a minimum of 30 years before he can be considered for release.
ass wept uncontrollably, covering his face his hands as he was told he would only be eligible for parole in 2040.
The victim's parents and family wept and hugged each other as the court heard for the first time that, after stabbing and slashing Miss Clough with a 3in (7.6cm) blade, he walked away momentarily, then went back seconds later to finish her off.
"As she lay bleeding you walked away but then returned and slowly, deliberately and cold-bloodedly slit her throat," Judge Russell said as he passed sentence.
"It is difficult to imagine a more horrific crime than this murder. Furthermore it was a crime motivated by real hatred and revenge.
"This was a deliberate, brutal and callous murder for which you have shown no remorse and no care for your own daughter.
"Jane Clough was a nurse who devoted her life to the care of others. She had the misfortune to become involved with you.
"She bore your child and then you murdered her, leaving your infant child without a mother and with the prospect of growing up to learn one day that her father murdered her mother."
The court heard that Miss Clough kept a diary, detailing her abuse and fears of Vass and what he might do.
She and her family, who held a protest outside court before the case began this morning, were "rocked and devastated" when he was bailed on the rape charges, leaving Miss Clough "extremely concerned for her safety".
She left home to live with her parents and recorded in her diary that she was worried "Johnny was going to do something stupid".
He had been relying on her to drop the charges.
Another entry read of fears he would "get his revenge", adding: "What's he going to do?"
Dennis Watson QC, prosecuting, said it was clear the motive for the murder was to prevent Miss Clough giving evidence.
Mr Watson said the couple met while both working at the hospital but their relationship was troubled because of Vass.
"He was a jealous man who wished to dominate and have complete control over Jane despite the fact that, unknown to her, he was carrying on a relationship with two other women at the same time," Mr Watson told the court.
By early 2009 Miss Clough was pregnant but Vass had become controlling and "sexually demanding".
In November that year she plucked up courage to report him to police, telling officers of the months of physical and sexual abuse and the repeated rapes even when she was seven months pregnant.
Text messages between the pair were read out.
Miss Clough sent him a message saying: "You have hurt, raped and reduced me to tears on countless occasions... and you want to get engaged and have more kids? Why?"
He replied: "We are staying together regardless of our problems."
A second text read: "Why should you come back? To push me about, grab me, rip my clothes off, make me cry..."
Another said: "You physically and sexually abuse me. You threatened to kill me the other night."
Vass's replies read: "Please can I come home... best behaviour promise", and "I do love you Janey. Either get pregnant or engaged. Your choice."
Vass was charged with nine rapes and assault in November 2009 and told a work colleague, an ex-boyfriend of Miss Clough, if he was found guilty he would kill her - but the threat was dismissed as "bravado".
When it became clear she was prepared to give evidence in court Vass decided to take "retribution", the court heard.
