Carl Spooner, 37, received a telephone call telling him the claims were to be investigated just hours before he was found hanged at his home in Rotherham.
The Pc, who had been honoured for disarming a knifeman four years ago, was already depressed after the claims caused him to be moved from his unit within South Yorkshire Police.
Coroner Nicola Mundy said that news that the complaint was to be investigated by the professional standards body was the “final straw” for the policeman, who had earlier in the week said he had contemplated suicide.
Mr Spooner had also told friends that he was looking for another job, after 11 years’ service with South Yorkshire Police.
He was found dead at his home in Bramley in October last year and had left a letter to his partner, Sarah Dennis – also a police officer – saying he was concerned the incident would affect him for life as “mud sticks.”
Recording a verdict that Mr Spooner killed himself, Ms Mundy said: “He was struggling with relationship difficulties with his partner. There was tension at work between him and a senior officer.
“But the most significant fact was the complaint and the nature of the complaint. His fear was how that would affect his work and the stigma attached to him.”
Ms Mundy also raised concerns about the way the complaint was dealt with by the force.
She said there was a lack of clarity over the nature of the allegations and the way they were communicated to Pc Spooner.
Ms Mundy said she would be writing to South Yorkshire’s Chief Constable and also to the Independent Police Complaints Commission.