The son of an unmarried mother became a zombie, introverted and fearing the next beating, lying soaked in urine at night in an attempt to dissuade sexual abusers from "dropping the hand", he told the hearing.
He lived at St Joseph's in Termonbacca, Londonderry, run by the Sisters of Nazareth order of Catholic nuns, in the 1950s after being born in abject poverty and abandoned by his parents.
The child was later placed in a dormitory full of youngsters crying for their mothers.
"It would break your heart, you would have to have a heart of steel and cement, I used to join in crying. I had not a clue what mammy meant," he recalled.
The former resident complained about his treatment to a cleric after leaving the home.
The response was: "You must never speak about this, you must understand... you and the other orphans are bastards. You are the product of an evil and satanic relationship. You never had a chance."
The witness said: "That was the day I left the Catholic Church."
The treatment of children in church-run residential homes is a key concern of the investigation being held in Banbridge, Co Down. It is chaired by retired judge Sir Anthony Hart and is considering cases in 13 residential institutions between 1922, the foundation of Northern Ireland, and 1995.
The witness said: "The truth is setting me free today more than this Commission knows. I have come here to tell the truth and as I am reaching out, I am reaching out in healing and trying to forgive but at this moment I cannot.
"I have waited 65 years to say this. When I was reared by the Sisters of the Congregation of Nazareth it was equivalent to being reared by the Taliban, such was their sadism, their lack of empathy, their fundamentalism, their lack of dignity to the little helpless boy," he alleged.
He was known as 10b.
"I was truly a feral child, an introverted child. When I came back from school I would be at the window on my own for hour after hour, night after night. I never played as a child," he told the inquiry.
He attended school with the opposite sex. It was also run by nuns, who warned the girls not to speak to "filthy" boys.
"The girls would look down on us like we were nothing," he said.
He wore ragged and inadequate clothing and claimed lying in pyjamas saturated in urine had left him with a medical condition.
The witness recalled visits of the bishop, his pope-like gestures and exhortations to pray for the conversion of the Russians, while the boy's immediate aim was wetting the bed to make him less attractive to sexual predators, even though it exposed him to public humiliation.
"If I didn't wet the bed, which was very unusual, it was my belief that, what sexual abuser would want to drop the hand or abuse a child that was saturated in their own urine?"
He described polishing floors until they shined, gangs of children using rags on their feet.
Senior boy overseers chanted: "Rub her back, rub her back, before I put this broom across your back," another witness said.
One youngster said the rhythm got faster and faster and if he could not keep up he was beaten.
He said he was deprived of the "nutrition" of a proper education, now absorbing books to make up - including an autobiography of Tony Blair.
He never played football or any other normal childhood pursuits.
Another victim said his Christmas presents "disappeared".
"You had no real personal possessions, none."
One witness testified that he just wanted to feel secure, for somebody to see him as a human being, not as a bastard but as a person with dignity.
He ran away from Termonbacca but was recovered time after time.
One nun smirked and said: "Welcome back, your majesty," the witness said.
"Then the beatings would start."
He never married.
"If anybody in the room knew what it is like to go through life without love," he said.
"A woman is beautiful, I see it all around me, I see the beautiful kids that I will never have."
He attributed this "life sentence" of loneliness to women in his childhood who brutalised him with beatings.
"Yet to make it worse these women professed to have a mission of love," he testified.
He said he was no longer angry. "I feel sorry in the sense that they must be mentally disturbed, they too were victims."
He claimed they often became nuns to give a family social status or to get rid of a problem, but added their vows went against their feminine instinct to have children.
"I feel sad for them because they are no longer in control of me."
Another witness married, after his years of no emotional involvement with anyone, and had children but his relationship ended.
"I found it very hard to stay in that relationship, even though I did it for my children. I did not want them ending up the way I was, so I made sure that they were all right - and they are all right."
Public hearings are due to finish in June 2015, with the inquiry team to report to Stormont's power-sharing Executive by the start of 2016.