Mariah Carey Fires Back at Publicist ... I Dumped You First!!!

Mariah Carey insists her publicist didn't quit her ... she canned the publicist.

TMZ obtained a letter which Mariah claims she wrote to famed publicist Cindi Berger, who has repped the singer for 15 years.

Mariah says in the letter, "I've done a lot of soul-searching this past year ... and I found myself asking if I was truly employing a healthy perspective (not to sound too Oprah about it all :)."

The singer goes on, "So I think it's time for us to take a break Cindi," saying she wants to "bring a fresh approach to this new phase in my career."

We reached out to Cindi Berger's office, and they say they never received the letter ... ever. Sources connected with the publicist say she's the one who decided to end the relationship with Mariah.

Things have gotten bitter fast. Mariah ended her letter by offering to put an ad in one of the Hollywood trade magazines honoring Cindi for winning a "Women of Power" award. Mariah's new manager, Stella Bulochnikov, tells us, they're pissed at Cindi because they think she leaked the story she quit Mariah, so they're not going forward with the ad.