The Devil Wears Prada star began dating the crooner in 2005, but they parted ways three years later amid speculation the singer had been unfaithful.

Neither star commented on the claims at the time, but Buble recently opened up about the love split, confessing he was "a jerk" for cheating on her.

The Canadian star, who is now married to Argentinian actress Luisana Lopilato, admits his three-year romance with the Into the Woods star fell apart after photos of him in another woman's bed surfaced.

He told eTalk, "I was a jerk and I was careless and reckless with the hearts of women I was with. And I got my karma. I earned it. I got my butt and heart kicked and it hurt me enough that I looked in the mirror and I didn't want it to happen again. If I wanted to be a happy guy and really fall in love, I would have to love myself... It's so cringy how I acted."

But Blunt insists she'll never be so revealing, telling U.S. DJ Howard Stern on Wednesday (30Sep15), "I never want to talk about it. I can't do it."

The actress did open up about her happy times with Buble, revealing the stars "had a good time" during their courtship, and although she is no longer in touch with the Canadian's family, she is still very fond of them.

"I love his family. I still do," she admitted.

Both stars have since moved on from the split - Emily married actor John Krasinski in 2010 and the couple became first-time parents to daughter Hazel last year (14). Michael has also started a family with Lopilato. The pair wed in 2011 and is expecting a sibling for two-year-old son Noah.