The widow of a retired solicitor killed in an alleged "road rage" stabbing walked out of court as the man accused of murdering him recalled the knifing.
Maureen Lock left the courtroom as a videoed police interview of Matthew Daley, 35, telling officers how he stabbed 79-year-old Donald Lock was played to jurors.
Mr Lock was knifed 39 times after crashing at about 16mph into the back of Daley's Ford Fusion car on the A24 at Findon, near Worthing, West Sussex, last July 16.
The minor crash happened after great-grandfather Mr Lock, who was returning from a cycling meeting, was forced to brake suddenly after Daley made an emergency stop.
In the videoed interview played at Lewes Crown Court, Daley described feeling "threatened and afraid" as Mr Lock drove close behind him before the crash. He said he saw Mr Lock in his rear view mirror looking "very angry".
He told officers: "I just saw someone very close and very angry and I wanted that scenario to stop because it was intrusive.
"It was aggressive. I know some people drive close sometimes but this person was very, very close and I didn't know why."
He added: "I thought he would see my red lights and think maybe he shouldn't be driving so close to me, because that's not how people are supposed to drive."
As Daley gesticulated to police how he knifed Mr Lock after they both got out of their cars following the minor collision, Mrs Lock left court.
Brighton and Hove Albion season ticket holder Mr Lock, who had recently been given the all-clear from prostate cancer, died at the scene as Daley sped off.
In the interview, played on the third day of Daley's trial, he also spoke of how he had recently split up from his girlfriend.
He said: "We were always falling in and out of actual love. We had been together for five years.
"We had a misunderstanding, but I was making efforts to win her back, and she was sending me kisses and stuff on my mobile phone."
Jurors have heard that Daley had been suffering from mental health problems for 10 years, and his family had "pleaded" with mental health experts to section him.
It was said he would often hear voices, hold his head "as if he was about to explode" and would at times grab the steering wheel while his mother was driving.
Last week the chief executive of Sussex Partnership NHS Foundation Trust wrote an apology to Daley's family, saying his care "should have been better", the court has heard.
As well as splitting from his girlfriend around the period of the killing, Daley had also racked up huge debts and shown signs of increased anxiety, his family said.
Daley, formerly of St Elmo Road, Worthing, denies murder.
In the police interview, Daley expressed sorrow for the death of Mr Lock.
He told officers: "I'm not happy that the man has died. I'm not happy that in the final minutes of his life he was in that much pain, and I don't want to be reminded of it.
"I feel very sorry about what I have done and I don't want to see anything like that happen in my lifetime again."
Daley was asked by an officer why he did not stop after inflicting the first wound that caused Mr Lock to fall.
"I don't know," Daley replied. "It's as if his anger has been put on to me and I'm trying to get rid of it."
He described feeling "afraid" and "scared" and wanting to be back with friends who had earlier that day put him in a good mood.
Asked why he had to use a knife on Mr Lock, Daley said: "Because it was in my mind to protect myself."
Daley was asked whether it was appropriate to react in the way he did following a minor road crash.
Daley said: "No, I don't think so but you have to remember that I was scared and all that had built up on to me."
He said he "didn't really consider" calling an ambulance, adding that he thought Mr Lock might become violent.
Daley also told how he had stopped taking medication he said was intended to help him sleep about about a year before Mr Lock died.
And he said he never touched alcohol, telling officers: "I care too much for my own body. I'm running most days for three and a half hours.
"I've learned that if I take alcohol and take a sleeping tablet, the next day isn't a good one."