The 74-year old, who cannot be named for legal reasons, pleaded guilty at Limerick Circuit Court to eight sample charges of sexual assault and defilement of the child.
The court heard he engaged in up to 10 sexual acts with the boy between June 2006 and March 2007.
The boy later slit his wrists and is receiving counselling for depression, the court heard.
The man’s defence argued the break-up of his marriage, prior to the sexual encounters with the boy, combined with a “depressive episode”, were mitigating factors in the crimes.
The man volunteered himself to gardaí and told them during interviews he believed the boy was 12 years old when he engaged in anal sex, oral sex and hand relief with the victim.
When asked by gardaí if he ever considered the boy’s age, he told them: “At the time, age never came into my mind.
“I felt like I was a guiding hand to him,” he said. “I didn’t feel bad. I didn’t see anything strange in it. I just went with the flow.”
Later, the man admitted he knew his depraved acts were wrong.
“I wish I was dead. I’m killing myself over it,” he told gardaí.
The accused said he never initiated the sexual acts but said he did ask the boy to perform oral sex on him a number of times.
The man said he received notes of affection from the boy, who he first met while cutting a hedge outside his home.
“The boy stopped outside his home and they had a discussion about the boy’s socks. He gave the boy a few bob,” said the defendant’s barrister, Andrew Sexton SC.
The victim told gardaí the man would “masturbate me and get me to put my penis in his anus”.
“He told me I was a special friend. I didn’t think it was right. I looked up to him as a father figure,” the boy had told gardaí.
John O’Sullivan, prosecuting, said the defence of mistaken age could not be used.
“His (two) sons have stood by heir father despite the nature of the offences and they have turned up in court today which is a sign of something (in his defence),” Mr Sexton said.
Judge Tom O’Donnell remanded the man on bail to appear for sentencing at the Circuit Criminal Court in Limerick on September 28.