The Xtra Factor host's relationship with the 18-year-old boyband singer caused something of a stir in the world of showbiz gossip.
Flack was even reported to have received death threats during her three-month fling with the 1D heartthrob. Now Caroline, 32, claims the romance taught her an important lesson.
"Everyone had an opinion on me and Harry, which was the hardest thing," she told The People. "I suppose they're entitled to their opinions but it was really tough.
"I learned the hard way. I learned a difficult lesson but I suppose looking forward it isn't a bad lesson to learn, is it?"
The couple parted company in January and, despite speculation that the romance might have been rekindled, Caroline instead took some time out with friends in the wake of the split.
She added: "In future the easiest thing is that I keep it to myself. I can't believe how much attention there as on me.
"I've been in Africa for a month with friends and it has been incredible to get away. We were helping people in the villages so it was a great experience."
Harry, meanwhile, appears to have set his sights on curvy reality star Kim Kardashian.
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