"She said: 'I'm a match, everything's fine'," Mrs Cullen said.
"And we just thought this woman's an angel. She's come into our lives, she's going to save my husband's life. And at this stage Billy couldn't work any longer because he was just rapidly deteriorating. Things got on their way and as far as we were concerned Nicola was going to be our donor."
Hutton told the pair that she was attending appointments and having tests carried out, and that the operation would be performed within months.
The court heard how Hutton also met with the couple, who gave her a Marc Jacobs gift set as a gesture of thanks.
Mrs Cullen said: "Then one day we got a phone call from the kidney team saying, 'There's no more we can do for you Billy'. We said, 'No, no, we have a donor'.
"We were told, 'No you don't have a donor. The kidney team did their own investigations and found this woman had never applied to be a donor. She had never so much as sent off a form or a phone call."
She said the family's "world came crashing down".
Hutton appeared before Belfast Magistrates' Court for sentencing on Thursday, where District Judge Francis Rafferty described her act as one of "abject wickedness".
He said she was an "emotional parasite" who fed off the couple's despair and "luxuriated" in offering them false hope.
"You presented yourself as an angel or a saviour and took the kudos and credit for that when you knew that you were as malignant a process in their life as any illness or sickness," the judge said.
"Your repugnant, repellent behaviour was exacerbated by the fact that you maintained your catalogue of lies and evasions, you required a member of the transplant team to take themselves away from the work they do, to sit in court and listen to you lie about them, their procedures and their professionalism," he added.
"At a time when the family were facing the gravest threat of all, the loss of a husband and a father, you decided to inject yourself into their world and spread poison, wickedness and false hope.
"A search process that exasperated the family, that caused them waking torment."
He set out how the couple had called off their search for a donor, overjoyed when Hutton informed them she was a match and offering "not just respite but rescue".
"A family saw you as their saviour and then (their) world stopped whenever your lies and your wicked machinations were exposed," the judge stated.
"I can only imagine the abject horror they felt whenever they realised that you had been lying to them all along."
The court heard that while Mr Cullen has since received a kidney from a legitimate donor, the six months wasted believing that Hutton was a donor could have had the most serious physical consequence.
In court, referring to Hutton's complaint about receiving internet abuse since her offences were disclosed, the judge stressed she had engaged in online actions intended to cause emotional torment and physical trauma.
"You lied repeatedly that you were on the transplant register, you lied about your medical appointments, you obtained gifts from these people, you sat with them," he told her.
"You led them on a dance where you deceived them at every turn.
"Like some form of emotional parasite, you were feeding off their despair and luxuriating in their hope and the kind comments online for doing what you were doing."
Mr Rafferty described his sentencing powers for the offence as "scarcely appropriate".
"I cannot imagine a more cruel act," he added.
Jailing Hutton for five months, the judge stressed: "People that live in the online world such as yourself need to learn that actions have consequences.
"Given the catalogue and cascade of cruelty that you visited upon these people, the only sentence I can impose is one of immediate custody.
"A family in the battle of their lives found you on their doorstep, offering help and salvation.
"All the time you knew what you were doing was an act of practised and consummate wickedness."
Following sentencing on Thursday, Hutton subsequently lodged an appeal and has been released on bail.