Liam Stacey, who was jailed for posting racist remarks on Twitter about Fabrice Muamba, has apologised.
Speaking to BBC Wales' Week In Week Out programme, the student claims he has paid a huge price for his drunken outbursts, made after Bolton midfielder Muamba suffered a cardiac arrest against Tottenham Hotspur on 17 March.
Stacey, who claimed his actions were "just drunken stupidity", was served a 56-day prison term for a racially aggravated public order offence.
"What I struggle to get my head around was the week or two before I was just a normal kid getting on with my work in university, getting on with life, playing rugby with all my mates, then a week or two later I was just going to prison, everything had been turned upside down," he said.
"It was a stupid, massive, massive mistake and I've paid a big price for it.
Muamba was discharged from the London Chest Hospital 30 days after he was admitted on St Patrick's Day, when his heart stopped working independently for 78 minutes.
The 24-year-old is continuing his recovery at his Cheshire home, however Stacey's future remains uncertain.
Swansea University suspended him pending the conclusion of disciplinary proceedings, as it remains unknown whether it will allow him to finish his degree course there.