The 19-year-old revealed on Twitter: "It's a song for people going through heartbreak - like I was when I wrote it.
"It means so much to me to be able to share what I was, and still am, going through, with my fans. I'm very proud of this song and I hope it gives my fans some insight into my heart."
21-year-old Gomez has since shared her thoughts on the song during an interview with US radio station KISS 98.5.
The brunette beauty said of Heartbreaker: "Honestly that's what's so beautiful though about music … Especially him, he's super talented at being able to use what he feels and interpret that through music.
She continued: "I mean it's what you do to grow as an artist, it's what I've done and many people do. It's sweet."
However the Come & Get It singer appeared to quash those rumours when the radio DJ asked whether or not she could bet on the lovebirds getting back together.
Gomez replied with a laugh: "You should bet for me to enjoy all the success that I have on my own and be independent and single until I know what I need to be doing with my life."