Chris Eubank says he would pull his son out of a fight if he was in the same situation as Nick Blackwell.
Eubank told his son, also called Chris, to avoid punching Blackwell in the head towards the end of Saturday's British middleweight title fight in London.
Blackwell, 25, is in an induced coma after being stopped in the 10th round.
Had the roles been reversed, Eubank Sr told BBC Sport that he would make "the only decision a father could" and "have the fight stopped".
Between rounds eight and nine, Eubank - a former world champion - was heard to urge his son to punch Blackwell's body rather than his face.
The fight was eventually halted in the 10th round by the ringside doctor because Blackwell's left eye was swollen shut.
Asked what decision he would have made had his son been in Blackwell's position, Eubank Sr said: "God willing, he's never in that position. But if he was, yes, I would have the fight stopped.
"It would alienate me from my son for life because I would pull him out. He would never forgive me. Never, even though he would be able to see that I made the right decision and the only decision a father could make.
"It's either that or his health, so it is not a difficult question."
Eubank Sr explained that he had told his son to avoid punching Blackwell's head in order to "protect" his opponent from further damage, adding: "Even in sparring, I tell Junior to stay away from the head because his punching is fast, powerful and dangerous."
Eubank Jr said he knew his punches were taking their toll on fellow Englishman Blackwell, who suffered a bleed on the brain.
"When my father said that… I thought that means this guy must be seriously hurt, that Nick must be in serious danger," he said.
"If you watch the last round, you can see me easing off. Any more punishment and the situation could have been even worse."
The 26-year-old also said he thought referee Victor Loughlin should have stopped the fight earlier.
However, Eubank Jr's trainer disagreed, insisting the referee and Blackwell's corner were right not to stop the fight.
"The kid was always there," said Ronnie Davies, who also trained Eubank Sr. "His corner couldn't pull him out. It was a title fight."
The British Board of Boxing Control has already said it was satisfied with how the bout, which took place at Wembley Arena, was handled.
Eubank Jr said news of Blackwell's predicament was "tough to hear".
He added: "We don't go in there to cause that type of damage to an opponent. It is never anything personal.
"No fighter wants to see the man after the fight in any type of serious condition. I'm not going in there to damage someone, I just went in to fulfil a lifelong ambition and become British champion."
He also said he had not thought about quitting since Saturday.
"As fighters, we know the risks," he said. "We know that we are risking our health every time we step in the ring.
"But it's a risk we're willing to take because with that risk comes great reward. I have the British belt and now I want to go for a world title."
Eubank Sr said he thought of Michael Watson when he saw Blackwell taken away on a stretcher.
Watson, 51, spent 40 days in a coma and suffered irreparable brain damage after fighting Eubank Sr in 1991.
- Listen - Peter Hamlyn, the neurosurgeon who helped save Watson's life, says other sports are more dangerous than boxing
Eubank Sr said his team would not celebrate Saturday's triumph until Blackwell had made a complete recovery.
The 49-year-old also rejected calls for boxing to be made illegal, insisting it would go underground and be unregulated, if it was banned.