The Canadian singer was devastated when his engagement to the British actress ended in 2008 but he thinks the way he dealt with it made the break-up the most important thing to happen to him, reported Contactmusic.
"When we were done I was devastated. I had to do therapy. I had to. I knew if I didn't change I'd never be happy in my own skin," Buble said.
"It was the worst thing that ever happened to me and the greatest thing. It ended through both of us being young and naive and making silly mistakes. I did so many things out of insecurity," he added.
"It would be weird for me to be in touch with her and her family as I have my own family now," he said.