A woman accused of a double murder said meeting killer Colin Howell was "the biggest mistake" of her life.
Hazel Stewart, 47, denies murdering her husband, Trevor Buchanan, 32, and her former lover Howell's wife, Leslie, 31, in May 1991.
At her trial in Coleraine on Wednesday, police interview tapes were played in which she wept bitterly.
"The biggest mistake of my life was ever meeting Colin Howell and I have paid the price," she said.
"Since that happened I lost so much of my life, I lost like a joy, a peace, contentment.
"It was like having a black hole every day I got up, every night I went to bed it was there, I thought about it 24-7. It never ever left me."
The jury of nine men and three women in Coleraine Crown Court listened as Mrs Stewart cried: "I would like to say sorry to Trevor's family. I can't imagine what it would be like to lose a son.
"I have a son and I love him very much. To David, my husband I love so much. Lisa and Andrew. They are my life and I have lost it."
In the final of a series of taped interviews played at her trial, Mrs Stewart was asked if there was anything else she would like to say.
"Just, that I'm so sorry," she said.
Earlier, Mrs Stewart admitted in police interview tapes that she was part of a plan to kill her husband but insisted she wanted no part in it.
The court heard Mrs Stewart tell police how she got rid of evidence.
They also heard how she encouraged her husband to take a sleeping tablet on the night of the murders.
She denied giving him the drug, but admitted that sedating him was also part of Howell's plan.
The jury also heard how Mrs Stewart destroyed a garden hosepipe which was used to gas the victims while they slept.
As well as cutting up and burning the hose on an open fire, she washed and replaced bed covers in the room where her husband was poisoned.
She also opened the window to get rid of carbon monoxide fumes and got clothes which Howell used to dress her husband before driving him off in a car with his dead wife.
On the police tapes, the court heard Mrs Stewart insist she had tried to stop Howell at the house on the night of the murders.
"I didn't want him to do it. I said I was scared. I didn't want it and when I saw the bag it was terrible. It was horrible and I knew what he was coming to do.
"And I didn't want him to do it. But Colin is a strong person," she said.
Mrs Stewart said Howell was on a mission and she did not get him stopped.
Police originally thought Mr Buchanan and Mrs Howell died in a suicide pact. The investigation was re-opened in January 2009 after Howell admitted that he gassed them and then fooled police into believing they had taken their own lives.
Howell is serving a 21-year jail sentence after he admitted his guilt last year.
The trial continues.