The pop star, who has just launched her new autobiography A Whole Lot of History, gave details of the rocky dynamic between Nadine Coyle and her fellow bandmates — Cheryl Cole, Nicola Roberts and Sarah Harding.
"Every day in Girls Aloud was a drama to be honest," Kimberley told Magic FM when asked about her time in the band.
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The songstress then went on to talk about how she drifted from Nadine, and defended herself for spilling the beans on the band's career.
"It wasn't so much that I needed everyone to know what my relationship is with each girl, just as you're telling the story, it naturally happens," said Kimberley.
"I mean, Nadine and I lived together in the beginning of the group, so it's obvious that at some point you're going to explain how that kind of drifting apart did happen.
"But it's obvious to see. She moved to Los Angeles and she wasn't around as much. And you just form close friendships with certain people."
Kimberley added that she mainly socialised with Cheryl and Nicola, while her relationship with Nadine and Sarah was more professional.
"As a group and working together it always worked brilliantly for us," said Kimberley. "Something really special happened when all five of us were together performing.
"But in terms of who I see outside of work, who I go on holiday with and go for dinner with, it would be Cheryl and Nicola."
Kimberley also gave a comment on the band's former manager Louis Walsh, calling him a "funny character". In her self-penned book, the blonde beauty divulges more details about the band's professional relationship with their manager.
Kimberley explained how Girls Aloud struggled due to Louis' absence in the early days.
"There seemed to be lots of hanging about and not knowing what was going on, and the main reason was that Louis seemed to have disappeared off the face of the earth," she wrote.
"Still, we motored on with recording our debut album. We followed that with roadshows and gigs at clubs and universities. The problem with the gigs was that we had no guidance from Louis whatsoever."