DUP leader Arlene Foster has claimed she might decide to leave in the event of a united Ireland.
The former First Minister was speaking on Patrick Kielty's Documentary My Dad, The Peace Deal And Me aired on BBC One on Wednesday.
Mr Kielty's dad Jack was murdered by the UFF in 1988. Three men were convicted in connection with the killing, but they were freed under the terms of the Good Friday Agreement.
On the 20th anniversary of the Agreement Kielty returned to his home town of Dundrum and travelled around to see if the historic peace deal had delivered on its pledge to create a new Northern Ireland.
Mrs Foster discussed growing up in the border area of Enniskillen, where her father was an RUC reservist. The IRA tried to kill him on the family farm and she spoke of the impact of the attack on her.
She claimed that someone locally had set her father up for attack. She also spoke about being a passenger on a school bus when the driver was targeted by an IRA bomb.
Mrs Foster told Mr Kielty she was not supportive of the Good Friday Agreement in 1998. "It was principally about the release of the prisoners, which to me was an anathema," she said.
"How can you allow people who have committed some of the most heinous crimes just walk free?" Mr Kielty asked Mrs Foster: "If the majority did want to join the Republic of Ireland, how would it feel to be a unionist, outside of the UK?"
She replied: "First of all I don't think it's going to happen.
"If it were to happen, I'm not sure that I would be able to continue to live here, I would feel so strongly about it. I would probably have to move."
Mr Kielty asked Mrs Foster where she would move.
"Well, that's the question. It's not going to happen so I don't have to worry about it anytime soon."
He was inundated with messages of praise after the programme aired, with many saying they were "lost for words". He revealed on the programme about the moment he found out his father had been murdered. "I was putting up Comic Relief posters (in school), which I hadn't asked permission for, it was the very first Comic Relief," he said.
"I was called down into the headmaster's office. I thought, absolutely certain, that this was what I was in trouble for. I walked into the headmaster's office, one of my dad's friends was there.
"I was told to sit down. And then everything just kind of goes into a sequence of events which you know you're going through but it doesn't feel real.
"From the point he says 'your dad's been shot'. I know that I said: 'Is he dead?' They said: 'Yes he is'. I remember the news report. One of the interesting things about making this documentary, I had never seen the news report in 30 years."
After the programme aired he posted a picture of his father on Instagram, writing: "Our Dad x Here's to the future..."