The 33-year-old slammed Helen, 28, following their departure from the Big Brother house last night.
Last year's winner Helen enraged viewers when she said Brian, 27, looked like a 'murderer slash rapist' during their special appearance on the new series.
Speaking to the Daily Star, Nikki fumed: "She will never be forgiven. He's good now, but those things she said to Brian were completely unacceptable and unforgivable. She took offence when he called her a 'bully', but a bully is what she is."
Helen's attack was too much for Brian, and he left the show early by climbing out of the house.
Nikki, who shot to fame on the seventh series of the reality show, alongside Aisleyne Horgan-Wallace, insisted Helen is worse than social commentator Katie Hopkins.
She continued: "She compares herself to Katie Hopkins. Katie Hopkins is more than she could ever be – Katie has class."
Do you agree with Nikki's comments? Let us know on Facebook and Twitter now.