A student jailed after making racist remarks on Twitter about footballer Fabrice Muamba has apologised and says he has paid a huge price.
Liam Stacey told BBC Wales' Week in Week Out programme how the comments - "just drunken stupidity" - turned him into a national hate figure.
Stacey, from Pontypridd, was given a 56-day prison term for a racially aggravated public order offence.
Muamba, 24, suffered a cardiac arrest on the pitch in March.
He recovered in time to attend the return fixture at the Reebok Stadium on 3 May.
Stacey told the programme, which is broadcast on Tuesday on BBC One Wales, he did not know why he made the remarks on Twitter, adding that it was a "stupid, massive, massive mistake and I've paid a big price for it".
"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.
The programme also went undercover to expose how so-called internet trolls - people who carry out anonymous online hate campaigns - target the most vulnerable.
It heard from the mothers of murder victims Rebecca Aylward from Bridgend, and Kirsty Wilkinson from Swansea, whose online memorial sites were attacked by trolls.
Kirsty's mother Catherine Broomfield said: "It's just beyond belief, it just hurts. I've already got a big hole in my heart as it is and these people just make the hole deeper."
One troll told the programme attacking others made him feel better.
Week In Week Out also enlisted the help of an unnamed internet expert to set a trap for the trolls who went out of their way to shock, offend and upset vulnerable people.
Nobody has been prosecuted for making comments about Rebecca Aylward or Kirsty Wilkinson.
However, the head of the Crown Prosecution Service for Wales said reported online crimes are treated exactly the same as offences committed "in the real world".
Jim Brisbane, chief prosecutor for the Crown Prosecution Service in Wales, said the vast majority of the population enjoyed social media and used it responsibly.
He added: "But there's now an opportunity to make it clear, for those who overstep the mark and abuse the privilege of being able to communicate in such a wide way, that the law that applies to other settings and other forms of communication can apply equally to what they're doing, and if that is not recognised then there may be consequences."
Superintendent Joe Ruddy from South Wales Police led the investigation into Stacey's case.
He said: "We in South Wales Police have seen an over 100% increase in the number of social networking-type occurrences in the last two years and that's probably just tip of the iceberg in what's going on out there."
While Fabrice Muamba continues to recover, Stacey's future remains uncertain.
Swansea University suspended him pending the conclusion of disciplinary proceedings.
On Tuesday, it said Stacey would remain suspended for the remainder of this academic year and is not allowed to return to campus.
But he will be given the opportunity to sit his final exams as an external candidate next year at another venue and, if successful, graduate in absentia.
He will remain excluded from the campus, the university said.
"We take the actions of this student very seriously, which is why he is no longer part of our campus community," it said in a statement.
"We are mindful that he has been given a prison sentence, and therefore has already paid a price for his actions.
"He has expressed genuine remorse and we are satisfied that he understands that his behaviour was unacceptable, and damaging to the university."
Week In Week Out is on BBC One Wales on Tuesday at 22:35 BST.