“An awful coldness ran through me when I realised, just an hour after saying he loved me, he’d taken someone’s life in the most evil way.”

The devastated ex-partner of Chris Halliwell has broken her silence to tell of her life with the cabbie who murdered Sian O’Callaghan. Heather Widdowson, 55, who lived with Halliwell at Ashbury Avenue, Nythe, believed the taxi driver was working long shifts to build a future for them both.

But Halliwell used his position as a trusted cab driver to abduct, sexually assault and kill 22-year-old office worker Sian, who was walking back from a night out in Suju on March 19 last year. He even texted Heather ‘I love you’ just one hour before the abduction. Halliwell was sentenced to life imprisonment on Friday after he pleaded guilty to Sian’s murder at Bristol Crown Court.

Heather said: “He’s a sick man. I don’t know why he did it. He had a good life. There was no reason for him to do it. He’s never shown any remorse or guilt. I don’t think he ever will. “He destroyed my life and made me feel worthless. The years we were together were a lie. “What he did that night is unforgivable. He has taken us to the edge of his nightmare and left us there.

“Everything I valued was destroyed: my home, my privacy, my family. We have suffered beyond words. “Chris rarely showed emotion and was always calm and controlled. Now I wonder if he let things build up in his head until it was too much to bear. “In all the time we were together he never showed any anger towards me. It never crossed my mind that he was capable of hurting me.

“Looking back, who knows what could happened. It sends a shiver down my spine to think I left my daughter with him for a few hours that week.” Describing the moment police informed her of Halliwell’s arrest, she said: “I felt numb. I stared into the darkness, shaking in horror. I couldn’t make sense of what had just happened.”

She added: “My heart goes out to all the families involved. I can’t believe the Chris I knew could hurt so many people. The man who did this is not the man I loved.”

Heather shuddered when she heard the gruesome court detail on how Halliwell had stabbed Sian in the head and neck with a six-and-a-half inch kitchen knife, as the brutal murderer had shown her the blade. She said: “He bought it a few weeks before it [Sian’s murder] happened. We went out somewhere and I leaned over in the car and saw it. He showed me it.”

Heather is now trying to start a new life. Eight weeks ago she started a part-time job, and she is expecting two grandchildren. She said: “You never get over it, you just learn to live with it. My heart goes out to his victims’ families. They’ll never get their daughters back.

“I hope Chris has a very long, lonely life. He is a cold, callous coward and I’ll never forgive him for what he has done. He’s destroyed so many families.” Heather met Halliwell in 2003 and moved in with him two years later. But their relationship got off to a bumpy start, as Halliwell got into debt.

Heather recalled: “He’d borrowed money from a friend and couldn’t pay it back. I offered to pay off £5,000. “But apart from money troubles we had a happy, loving relationship. We both worked odd shift patterns but we managed to find time for each other. Heather also revealed Halliwell had a dark past.

She said: “He told me he’d done ‘horrendous’ things when he was young but I didn’t want to know what.” She said their relationship changed at Christmas 2010 when his mood changed.

Remembering the night Sian disappeared, Heather said: “Chris went to work early. It was a Friday night so I was off from work. “Later that night, about 1.30am, I sent him a text to see how he was doing. He said business was good and I got ready for bed. He text me again at 1.45am saying: ‘I love you’. “The next morning he was up early, which was unusual. Normally he didn’t get out of bed before 11am on Saturdays. “He said he had a lot to do, and went to the car wash.”

Then at 12pm on Wednesday, Halliwell woke Heather, who was asleep in bed, to say the police were coming round. “Chris said they were interviewing all the taxi drivers in the area,” said Heather. “The questions seemed normal and Chris was relaxed. But at the end the officer took out a DNA test. I watched the colour drain from Chris’s face. Reluctantly, he gave a sample.”

The next morning at about 11am, Heather was woken up by a loud knock at door. It was the police telling her Halliwell had been arrested for murder. She said: “I fell apart. I couldn’t believe what they were telling me.”

The next day police revealed there was a second body, which turned out to be Becky Godden-Edwards. Heather said: “I couldn’t believe what they were telling me. In all the years I’d been with Chris, he was hiding this sick secret. I wondered if I’d ever really known him at all.” In June, police let Heather move back to her home in Nythe. She said: “I had my window smashed, cars would slow down and stare through the windows like my home was a tourist attraction. Youths would shout abuse and I was even called nasty names.”

After hearing Halliwell was jailed for life, Heather said: “No punishment will repay what everyone has lost. But if life really means life, then I guess we have to be satisfied.”