The 56-year-old, named locally as Sally Challen, drove 112km from her Surrey home to Beachy Head, East Sussex. She was persuaded to leave the edge of the clifftop by specialist police officers after two hours.
It is understood she told officers on the 500ft cliff that she had killed her partner, named by neighbours as Richard Challen.
He was found dead by officers from Surrey Police just after 1pm on Sunday in the home they once shared in Ruxley Ridge, Claygate, near Esher.
The couple, who have two sons, split up around a year ago.
A postmortem examination to establish the cause of Richard Challen’s death was taking place at the Royal Surrey County Hospital yesterday.
Challen sold his car dealership, Westlake Garages in Richmond, south-west London, to Paul Arulndran when he retired in August 2008.
Arulndran said: “It’s a big shock. He was a very good man. I only met her twice, but he would come in all the time to see how I was getting on.”
Arulndran said Challen told him he had separated from his wife.
A neighbour said the couple had been experiencing financial problems.
He told the Daily Mail: “They separated about a year ago and she moved just around the corner. The rumour was that he was seeing prostitutes and that is why she left him.
“They have two sons. The older one lived with Richard and the younger one lived with her.”
Challen received a 51-week prison term suspended for 18 months in 2006 when he crashed his Ferrari at a race track in Belgium, then invented a hit-and-run accident to claim £35,000 (€43,000) for repairs.