Real Housewives of Atlanta viewers already saw NeNe Leakes, 43, and Kim Zolciak, 32, square off during an ugly bus brawl during the show's January 16 episode -- but the drama is far from over!

When asked to describe the incident during part one of The Real Housewives of Atlanta reunion special (airing Sunday at 10 p.m. EST on Bravo), Leakes says she was appalled at how Zolciak treated her assistant, Sweetie.

"I'm not going to sit with a group of people and listen to somebody talk down to someone. I am not going to sit in a conversation and have somebody point their head in my face and say, 'F*** you, bitch!' several times," Leakes explains. "I'm going to react. I think you can dish it out but you can't take it."

Tensions running high, Zolciak then interrupts Leakes to explain her side of the story.

"You started the argument!" she shot back. "You were screaming and yelling on the bus and you responded. When you call my assistant a slave, I'm going to say, 'F*** you, bitch!'"

Part one of The Real Housewives of Atlanta reunion special airs Sunday at 10 p.m. (EST) on Bravo.