Desmond Lee said yesterday he was "petrified" after realising he had accidentally killed Christopher Pratt last August while they were having sex.
He told Leeds Crown Court he did not want to go back to jail and thought if he phoned the police "they wouldn't believe me because of the old saying if you have done it once you have done it again."
The jury has heard Lee was jailed for life after he was convicted by a jury in November 1990 of the murder of Shirley Carr, 46, who was asphyxiated the previous November while he was lodging at her home in Henry Street, Thornton, Bradford.
He denies murdering Mr Pratt, 51, a civil servant from Grantham, who was visiting him at his home in Sackville Street, Dewsbury, on August 16 last year.
Mr Pratt's naked and decomposing body was found by a jogger on Scammonden Moor, near Huddersfield, on August 26. His larynx and the hyoid bone in his neck had both been fractured.
Lee told the court he was 19 when he began a relationship with a man in 1989 with whom he was infatuated. "I thought he was the love of my life."
They were staying at the home of Shirley Carr when the man failed to return one night and he then discovered his lover had returned to his ex-partner.
He told the jury at the time he was an alcoholic and was drinking heavily, upset about what had happened, when Ms Carr began taunting him about it.
"I just got hold of her by the shoulders, shook her and we ended up on the floor and my hands covered her mouth and nose and I suffocated her."
He told his counsel Alan Newman, QC, he was too scared to tell police and later left the body in the house. He was subsequently arrested and convicted of her murder, spending 14 years in jail being released in 2004.
He met Mr Pratt at a gay club in Dewsbury last year and had sex with him after returning with him to his home in Grantham.
On another occasion he was involved in a threesome with Mr Pratt and his gay partner.
On August 15 Mr Pratt travelled to visit him in Dewsbury and they had sex that night.
Lee told the jury he had drunk about a litre and a half of vodka, some Bacardi, and Stella, as well as taking cannabis, cocaine, and amyl nitrate.
The next day they were again having sex, on a mattress in the living room, after he had been drinking. He said he reached over to put a glass of water down and get some drugs with one arm while the other was under Mr Pratt's neck below him.
He took a couple of puffs from a cannabis joint, snorted some cocaine before having another drink of water and then reached for the amyl nitrate and inhaled some up both nostrils.
He estimated he must have been reaching over Mr Pratt for about four minutes. When he finished having sex he realised Mr Pratt was not moving and ran into the bathroom to be sick after seeing his dead face.
The jury was shown a video of Lee demonstrating by using a first aid mannequin what had happened.
He admitted the next night he covered a security camera outside his flat while he moved the body into the boot of Mr Pratt's car and drove it to the moor where he dumped it.
Under cross-examination by David Hatton QC prosecuting, Lee agreed while Mr Pratt's body was "still warm" in the flat he had used his debit card to pay his phone bill. "I wasn't thinking straight," he said.
He spent that evening using Mr Pratt's car to help friends move home and the following morning ordered 212 in goods from Asda on Mr Pratt's credit card. "I was just numb," he said.
The trial continues.