The Sydney mother of a 10-month old who was left in a bath with the hot water running says it was "a nightmare" to see her comatose boy lying in hospital for nearly a month.
The infant suffered burns to about 40 per cent of his body when Atare Tepania, 24, left him unattended to smoke a cigarette in November 2015.
When Tepania returned to the unplugged bath, he picked the screaming boy up by one arm but dropped him on the tiled floor before pouring cold water over him. The baby was so badly burned his skin was peeling off.
He now hates baths, doctors, medicine and hospitals, his mother told Penrith District Court on Friday.
"Watching your own child laying on a hospital bed in a coma not knowing if he was going to make it or not was a nightmare," she said through tears. "How could someone do something so horrible to a sweet, innocent child."
Tepania pleaded guilty in August to reckless grievous bodily harm and assault occasioning actual bodily harm.
After the incident, he tried to feed the boy a bottle but pressed it so hard the boy's mouth bled.
On Friday, he said he also lied to police about striking the boy because he felt "under pressure".
Court documents show Tepania, who tested positive for methamphetamine, told officers he was "hungover ... really bad" and had "f***ed up". The court heard Tepania, who endured a troubled childhood, drank for "an extended period of time" before the incident, also mixing the alcohol with drugs for two consecutive nights.
He said he was too ashamed to talk to the woman, but on Friday offered a tearful apology.
"I'm really sorry," he said, without making eye contact.
"I know what I did was wrong." Tepania said he thought about his actions every day and also had nightmares. "I'm crushed by it," he said.
He was also targeted by other inmates at Parklea jail who heard about his case on the news and said they called him "putrid".
On one occasion, a prisoner threw boiling water and jam over Tepania, causing skin on his face to peel, while in another incident he was bashed by three others.
Psychologist Maria Quinn described as "simplistic" his understanding of the effect of drugs and alcohol upon his capacity as a parent.
He only understood that he shouldn't drink or use drugs in front of the children, she said, but not the broader consequences.
Judge Robert Sutherland reserved his sentence until October 27.