After being interviewed apart, the defendants were allowed to speak together and before long were pointing the finger at each other.
In the early hours of August 9, Gurjinder Singh resumed discussions with police alone, during which he said he was pressured into helping with the killing.
Kaur would tell him her husband was beating her every day because he had found out about the affair the defendants had months earlier, he said.
"She has used me. I'm lost for my family," Gurjinder Singh said, sobbing.
When he approached the car on the night in question he said the window was halfway down and he reached in to hold the victim while Kaur stabbed him.
"I just hold and push him. I don't see inside," he said.
Gurjinder Singh told Detective James Gemmell the plan had been initiated about a week earlier by Kaur through a series of hand-written notes, which he said could be found in his car and at their workplace in Penrose.
The notes will be produced for the jury this week.
Gurjinder Singh's lawyer David Niven raised issues about his client being interviewed after being awake for so many hours and about the absence of an interpreter.
But Mr Gemmell defended his actions, saying the defendant chose to talk after being given standard warnings.
Crown prosecutor Natalie Walker said the defendants had begun an affair months before Davender Singh's throat was slit.
After 130 calls and more than 1000 text messages in the space of three months, It is alleged their respective partners discovered the relationship and electronic communication between the couple ceased, forcing them to exchange notes at work.
The trial continues.
