Former president Mary McAleese has revealed her younger brother was "sadistically" abused as a child by Father Malachy Finnegan.
Dr McAleese said that her youngest brother was abused by paedophile priest Fr Finnegan, who was the president of St Colman's College in Newry at the time.
She has now called for a full inquiry into accusations against the late priest and those who held senior positions within the school and diocese at the time.
Speaking on The Sean O'Rourke Show on RTE Radio One, she said: "My youngest brother, my baby brother, was seriously, physically and sadistically abused by Malachy Finnegan.
"My mother, almost 90 years of age, had to discover that from an article in the Belfast Telegraph three weeks ago.
"Four of my five brothers went to that school.
"It shouts for an inquiry and I think an independent inquiry is warranted."
She said that there are many survivors of abuse suffering "a mountain of hurt".
"He was 49, he was seven when I got married and left home," Dr McAleese said.
"He's not the only one, there are legions of silent sufferers who carry it through their lives and it remains unresolved and causes so much suffering.
"The sad thing is that here we are, 20 years after the new guidelines were introduced, all of the secrets were supposed to be out but here we are, there's a mountain of them and a mountain of hurt."
The Bishop of Dromore Dr John McAreavey hit the headlines earlier this month after he resigned following the controversy over his officiating at Fr Finnegan's funeral.
Fr Finnegan died in 2002 and has been accused of sexual abuse by 12 people.
Meanwhile, the former president also revealed that she has "received neither an acknowledgement nor a reply" to a letter she wrote to Pope Francis after the Vatican declined to approve her taking part in a conference in Rome.
"I accept the authority of the Pope, of course I do. But do I accept absolutely everything the Pope says? I don't have to. No," she said.
On the Eighth Amendment, Ms McAleese said she "has a lot of reading to do", having been out of the country last week.
"I'm comfortably a member of the Catholic Church, comfortably uncomfortable sometimes," she said.