Dan Blackwell - the younger brother of former British middleweight champion Nick - has retired from boxing after fearing for his sibling's life.
Nick Blackwell suffered a bleed on the skull in a loss to Chris Eubank Jr in March and was put in an induced coma.
Dan, 23, a journeyman who won only seven of his 61 fights but was stopped just once, decided to quit before learning his brother would recover.
"I thought my brother was dead - just that thought..," he said.
The father-of-two said he did not want to put his family through what he experienced when waiting for Nick to wake in hospital.
"What I went through with Nick was horrible," he added.
"I sent a message to my girlfriend [Chantelle]. I was a mess on the night, saying 'I'm sorry for what I put you through, if you felt 1% of what I'm feeling now. I'm never going to box again'."
The injuries the 25-year-old suffered mean he will never again fight as a professional, and Dan admits he is "upset" at the thought neither will box in the future.
"Not being able to do it again is horrible," added the full-time bricklayer, whose only stoppage defeat came against Welshman Liam Williams.
"My mum [Cindy] has never liked me and Nick boxing. But I've always done what Nick's done.
"I don't want to be still in boxing, fighting and all the rest of it, knowing he can't fight. With him, I don't think it's sunk in yet that he's not fighting anymore."