A civilian police worker called 999 and told the emergency operator he had killed his wife, a jury heard.
Stephen White is alleged to have made the dramatic call minutes after trying to mow down his estranged wife Tracy and her lover Martin Buck with his car.
White, 34, is accused of attempting to kill the couple on the evening of June 27 last year after he saw them walking her dog in Creasy's Drive, Crawley.
He is alleged to have mounted the pavement and driven into the couple, knocking Mrs White into the air. While she lay injured in bushes at the side of the road, he is accused of chasing after Mr Buck screaming "You are shagging my wife" before getting back into his red Rover and driving again at his rival.
White, of Beechy Road, Crawley, who works as a Metropolitan community support officer, is said to have driven into a wall before fleeing.
Neither Mrs White nor Mr Buck suffered serious injuries.
The court heard soon afterwards he rang the police to tell them he had killed his wife and he was hiding in woods.
In a recording of the call played to Lewes Crown Court, White was heard saying to the operator: "I have killed my wife. Send an ambulance.
"Shut up and listen. I have knocked her over in a car and I am hiding. I am going to kill myself. I am not going to prison. Do you know what they do to police in prison? I am an officer in the Met.
"I do not know what to do. I have killed her. I have had a nervous breakdown. I saw her with her boyfriend walking along the road with my dog. I lost control. I have a knife and will slash my wrists."
Referring to Mr Buck, he said: "Get the guy off the street because if I find him I will kill him."
Earlier the jury heard the couple had a history of problems during their nine-year marriage. Three days before the alleged attempted murder White, who suspected his wife was having an affair, punched her during a row.
White, who has suffered from mental illness for five years and received treatment for post-traumatic stress disorder, was arrested by police and cautioned for assault. He moved out of the couple's home.
Two days later he tried to kill himself by taking an overdose.
White has denied attempting to murder his estranged wife and two charges of attempting to murder Mr Buck. He also denies attempting to cause grievous bodily harm to the couple and a charge of dangerous driving.
The trial continues.
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