The 'Hangover' star – who used to be married to the actress Jennifer Esposito – was told by a former lover that their relationship was over while he was in Peru and battling altitude sickness.
He told UK station Radio 1: "The worst time I was dumped was overseas on a bad line of a telephone. I was in Peru with an oxygen tank because I hadn't acclimatised properly. It was the worst time. She's a sweetheart though."
The 36-year-old actor was previously in a relationship with 'Bridget Jones' Diary' star Renee Zellweger and has in the past been romantically linked to former 'Friends' actress Jennifer Aniston.
Bradley recently starred alongside Academy Award-winner Robert De Niro, who he has described as "the greatest".