A jealous martial arts expert who strangled his partner after learning that she planned to leave him for another man was jailed for life today.
Alan Jermey was told he must serve at least 16 years after being found guilty of murdering Mercedes executive Kirsty Wilson by an Old Bailey jury.
Jermey was "obsessive" about Miss Wilson, the mother of his two children, and could not stand to let her go.
Judge Martyn Zeidman today said he had done a "terrible thing" by killing his "kind, vibrant, beautiful" partner.
Jermey, a car salesman with a black belt in kung fu, used his skills to throttle her, leaving few external injuries.
He set her body alight to try to make it look as though she had died in a fire but the blaze failed to take hold.
Jermey hatched a cold-blooded plan to kill Miss Wilson after learning that she planned to leave him for her married boss, Simon Goddard.
Miss Wilson signalled an end to their nine-year relationship when she told him: "I can't see us spending the rest of our lives together."
But Jermey was not prepared to lose her, their two daughters, or the four-bedroom house where they lived together in Woking, Surrey.
He secretly ordered a 100,000-volt stun gun over the internet so he could knock her out before killing her in August last year.
After pouring petrol over her, he arranged her body to make it look as though she had fallen asleep watching television and clambered on to an extension roof with their two daughters as one of them cried: "I want Mummy."
Jermey, who worked for a car firm near Heathrow, claimed in court that he had gone to bed early and left Miss Wilson downstairs when he was woken by an explosion and was prevented from saving her by thick black smoke.
But when firefighters arrived, they found there were only a few wisps and noticed he seemed calm and unconcerned about what had happened to her after they rescued him and his daughters.
Jailing him today, the judge told Jermey: "You have done a wicked act, murdering the mother of your own young children."
He said the killer had "imposed a life sentence of weeping" on his partner's parents and caused a "devastating blow" to his children.
The judge told Miss Wilson's parents, Peter and Sandra Wilson, from Bradford, West Yorks, who were in court: "Nothing can bring Kirsty back but I offer even at this late stage my condolences."
Mr and Mrs Wilson, who both wept as they gave evidence at the trial, described their daughter as popular and beautiful, and "the kind of woman who turned heads".
Mrs Wilson said Jermey was "obsessive" about her daughter.
"When I would say 'That's a pretty girl on the television', he would say 'No, she's not as nice as Kirsty, there's nobody as nice as Kirsty'. He thought she was really something special," she said.
Mr Goddard, who was Miss Wilson's boss at a Tony Purslow Mercedes dealership in Basingstoke, Hampshire, had already left his wife and two children for her. He said they were "very much in love" and planned to marry.
"I still find it hard to accept that all of our dreams and plans for the future will never materialise," Mr Goddard added.
When Miss Wilson told Jermey in May last year that she planned to leave him, he at first seemed to have calmly accepted it.
They stayed together in the house and made arrangements for the split but cracks began to appear in the facade and one night she found him crawling on the floor looking at her mobile phone.
Jermey, who was also several thousand pounds in debt, killed his partner in August, the night before their property was due to go on the market.
Sarah Forshaw QC, prosecuting, told the jury: "The time was fast approaching when she was going to leave him.
"That night, when the children were upstairs asleep, he killed her. He arranged her dead body on the floor. He went out to the garage where he kept petrol cans for the lawnmower.
"He poured petrol over, particularly over her head and her neck and he set fire to her.
"He was particularly anxious that he may have left signs around her that identified himself as her strangler. He expected the fire to take hold immediately and for the house to go up in flames. The fire never really took hold."
Detective Inspector Paul Monk said: "Jermey was consumed with jealousy and rage. He violently murdered the mother of his children and set fire to her, hoping that their family home would go up in flames, and crudely covered up the killing.
"He may have perversely believed that, by taking Kirsty's life, he could ignore the collapse of their relationship and retain full custody of their children. In fact, his wicked act has deprived two young girls of both their parents."