Emma Spence, the sister of Ulster Rugby's Nevin Spence, was treated in Belfast's Royal Victoria Hospital for the effects of inhaling fumes following the weekend slurry tank tragedy.
Her two brothers and father were overcome by gas after falling into the tank at their farm on the Drumlough Road in Hillsborough, Co Down, on Saturday night.
The talented 22-year-old rugby player died along with his 30-year-old brother, Graham, who was married with two children, and their 52-year-old father, Noel.
Ms Spence, a well-known artist, was discharged from hospital last night as relatives revealed that the three men had died trying to save each other.
A book of condolence was opened yesterday at Ulster Rugby's Ravenhill ground in Belfast, while the team's RaboDirect PRO12 game on Friday in Italy against Zebre looks set to be postponed.
Ulster Rugby chief executive Shane Logan said: "It will almost certainly be postponed."
Funeral arrangements have yet to be finalised.
Irish Tanaiste (Deputy Prime Minister) Eamon Gilmore visited Ravenhill to pay his respects on behalf of the Dublin Government.
Mr Gilmore described the accident as a "deep, deep tragedy". He said the whole island had been rocked by what had happened.
Northern Ireland's Deputy First Minister Martin McGuinness said the Stormont Assembly had been rendered a "solemn and quiet" place as a result of the tragedy. He added: "The only good thing out of this is that Emma thankfully was spared and is now out of hospital and back home with her family."
Former Stormont first minister Ian Paisley expressed confidence that the family's strong Christian faith would sustain them.