The singer/actress has paid tribute to the mixmaster - real name Adam Goldstein - who was found dead in his New York City apartment after a suspected drug overdose.
In a statement Moore says, "I am absolutely heartbroken. For those of us lucky enough to have known him, Adam radiated a contagious exuberance for life and also personified the very definition of a true friend.
"To say that he will be missed beyond words is an understatement. My heart goes out to his loved ones."
The couple dated in 2007 and rekindled their romance shortly after Goldstein survived a horrific plane crash in South Carolina last year (08).
Moore, who married rocker Ryan Adams in March (09), was spotted filming upcoming movie Swinging with the Finkels in London the day authorities discovered her former beau dead.