A "bunny boiler" ex has been jailed for life after she killed her love rival with a stun gun and a kitchen knife.
Sarah Williams, 35, shot businesswoman Sadie Hartley, 60, with a 500,000 volt stun gun as her unsuspecting victim answered the door to her home.
Then with "demonic savagery" she used a kitchen knife to stab the semi-paralysed mother-of-two through the face and neck, inflicting more than 40 stab and slash wounds, before leaving her in a pool of blood in the hallway of her £500,000 home in Helmshore, Lancashire.
Hartley was home alone, while her partner Ian Johnston was away on a skiing trip in the Swiss Alps.
Williams, described as a "bunny boiler" and "kept woman" already in a relationship with a wealthy 75-year-old "sugar daddy", amid affairs with other men, had had a brief fling with ex-fireman Johnston.
He had dumped "obsessive and jealous" Williams and begun a new life with Hartley - but explicit photos and sex texts continued between the pair while Williams plotted the "perfect murder" for 18 months to kill her rival and win him back.
She was convicted of the murder at Preston Crown Court, and ordered to serve a minimum term of 30 years before parole can be considered.
Her accomplice, horse riding instructor Katrina Walsh, 56, who kept notes detailing the murder plot in her diary, was also jailed for life with a minimum term of 25 years.
Both women, from Chester, had denied murder and blamed each other during the seven-week trial.
Passing sentence Mr Justice Turner said the stun gun and stabbing of "loving mother" Hartley meant she was "slaughtered like an animal" adding: "Neither of you have shown the slightest remorse."
He told the pair: "Let no-one believe this was a crime of passion. It was a crime of obsession, of arrogance and of barbarity, but above all a crime of pure evil."
Hartley's daughter Charlotte said that she was unable to explain "how much pain and horror" it had brought to her family.
She said that the last time she spoke to her mother was to tell her that she had got engaged while in Hawaii.
"It is the most shocking and unforgettable news," Charlotte said.
"The two women who murdered my mum plotted for months to do these things and I don't know how a human being could do this to another human being.
"It's like living a nightmare. I will never be able to forget how frightened and scared my mum would have been that night in her own home where she is meant to be safe."
She continued: "My mum will not see me get married and will never have the chance to meet my children. Thinking about this will haunt me for the rest of my life. The pain and torture of knowing I will never see, speak to or touch my mum again breaks me."