Fiona Linahan, from Downpatrick, travelled with her daughters Georgia (7) and Maeve (5), as well as their friends Katie Coyle (8) and Carolyn Fitzsimmons (7).
"Jesy is not well, so we hope she's okay, but we'll probably see them again soon," Fiona said.
Georgia added: "We're a bit disappointed because mummy and daddy had to take off work and we travelled from Downpatrick, but we hope that Jesy's okay."
Travelling from Derry were GCSE students Claire McLaughlin (16), Emily Watson (15) and Eve Graham (16).
Claire described the moment she heard the bad news. "We came outside and a man came out and told us Jesy's sick and it was cancelled. We thought he was joking," she said.
"It was just like One Direction. We came the whole way down today and now we have to go back."
Emily added: "We thought he was taking the hand. We asked, 'Are you sure?' We've been looking forward to it since October."
Eve said: "Hopefully it can be rescheduled this week, but if it's during school it's a bit more stressful because we've got GCSEs coming up so we don't really want to be taking time out."
Mandy Redpath, from Belfast, had been looking forward to the concert with her nine-year-old daughter Alex. Joining them were friends Ally Dougan with her daughter Katie (8).
"We weren't even told," said Mandy. "They didn't even come out and announce it half-an-hour before we were due to go inside."
Ally said: "How come it's Belfast? I think we should start to take it personally. It hasn't happened in Dublin, it hasn't happened in England. People have work - it's not fair. Some people have even hired out buses to get here."
Clearly angry at the last-minute cancellation, a tearful Katie added: "I hate them - I do. Jesy is the worst singer. She can't sing at all."
Cillian Dornan (40) travelled from Londonderry with his wife, Claire (36), and their daughter Ellie (9).
"They were so excited last night, they hardly slept thinking of Little Mix," he said.
"Taking time off from work, it's very hard to come up from Derry."
Claire added: "This was a Christmas present from Santa and they were really excited when they got the tickets."
Ellie simply said: "The girl got sick and now we're all disappointed."
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