It seems obvious to me, by Denise's own words and actions, that Brandi's story is true. When Garcelle asked Denise if she wanted to know what was being said, Denise replied "If it is a dangerous area, not on camera." Teddi then said that it was already on camera, and that there was going to be more. Denise replied that "there is no truth to that". How did she know what "that" was, since at that point Teddi had not revealed what was being said about Denise?
Now if someone came to me and said there was some horrible rumour about me, I would say "let's hear it" because I have nothing to hide. I wouldn't worry that it could be a dangerous area, because I don't have any.
From what I saw on this episode I have no problem believing Brandi. I don't care one way or the other, it's not my problem. But I do believe Denise is the one lying.