Clutching a crumpled white tissue in her hand, Ms Andrews, 28, was accused by David Crigman QC, for the prosecution, of making up a "road-rage" attack to hide her killing of the man she professed to love.
Mr Harvey, 25, had been stabbed 30 times as the couple drove home along country lanes near their home in Alvechurch, Worcestershire, in December. Ms Andrews had claimed that he had been stabbed after being chased by another car.
But the jury at Birmingham Crown Court was told that despite publicity about the murder no witness had come forward to say they had seen a pursuit between two cars.
Mr Crigman accused Ms Andrews of repeatedly stabbing Mr Harvey in the back as he tried to escape from a frenzied attack following a " blazing row". He asked her how she could explain blood splashes found at the rear of the couple's Ford Escort.
Ms Andrews denied that she and Mr Harvey had rowed about the father of her seven-year-old daughter, or that the row had exploded into violence.
Ms Andrews said: "I am not going to admit to anything I have not done." Mr Crigman said: "Lee Harvey retreated from his attacker at the rear of the car did he not?" Ms Andrews replied: "I don't know."
Asked if she was the attacker, she said: "No, I was not."
Ms Andrews admitted no one had come forward to support the crucial part of her story but blamed the police for not asking potential witnesses about a Sierra car which was allegedly pursuing the couple.
"You are a woman of considerable deceit," said Mr Crigman. Ms Andrews responded: " No I am not, I am trying to help the best I can, but it was hard going back along that road and I don't want to go."
Ms Andrews denied that she had exploded in a vicious temper on the journey. "The relationship was not violent but stormy. He had been violent towards me." The case continues.