Rumors have circulated for months, but now it's official -- NeNe Leakes will not be returning to "The Real Housewives of Atlanta" ... she says so herself.

The longtime 'RHOA' star just posted a video stating it clearly -- she's made the call to NOT be a part of season 13. NeNe says she made the difficult decision after an "extremely long, exhausting, tiring, emotional" contract negotiation.

NeNe stresses things were emotional for both sides during the process, and fights back tears before reflecting on her time with the show ... which started for her back in 2008.

Though Leakes only explicitly says she's out for season 13, her message suggests this is more of a farewell for good.

She says ... "I'm just so happy that I can say that I was part of a genre that opened up a door for Black ensemble reality shows. I want to thank everybody that has looked up to me over the years. I want to thank Bravo for all the memories. Thank you to the cast for all of the memories."

The video NeNe posted on her YouTube page includes her 'RHOA' highlights from over the years.

In August, NeNe went on a tweeting spree amid her contract negotiations and seemed to call out her castmates for not protecting her or standing up for her ... though she didn't name names.

NeNe is one of the reality series' biggest stars, known most for her friendship/falling out/reconciliation with Kim Zolciak-Biermann ... and her rivalry with Kenya Moore.

'RHOA' is currently in production for the upcoming season on Bravo.

A spokesperson for the network tells TMZ ... "We wish Nene all the best in her future endeavors and thank her for sharing her journey for over a decade with the fans of 'The Real Housewives of Atlanta.' She’s been instrumental since the start and will truly be missed, and maybe one day she’ll hold the peach again."