The I Will Never Let You Down hitmaker wrote the track after splitting from the Scottish Dj, and she was determined not to hold back, comparing her ex to the devil.
Lyrics in the song, called Poison, include, "Like a serpent/From the Garden of Eden/You are like poison/Running in my blood" and "I open up my windows/I'm so sick of breathing/Every day I'm trying/But I don't remember who I was before you came."
Although Ora has not confirmed who the song is about, fans are speculating the mystery man in the lyrics is Harris.
The 23 year old tells Clash magazine, "This is about my bad luck with love."
Ora split from Harris in June (14). She previously dated Kim Kardashian's younger brother Rob, and has recently been linked to fashion designer Tommy Hilfiger's son, Ricky Hil, after they were spotted on a night out in London in July (14).