5ive star Ritchie, who welcomed baby Ella Rose with Natasha last year, branded Farrah a "b*tch" after watching the Teen Mom star cause havoc during an afternoon tea party.
American Farrah had laid into Natasha and fellow housemates - including Gail Porter and James Hill - as part of a secret task to make them "cross", however she appeared to take it too far.
Taking to Twitter after seeing Atomic Kitten's Natasha burst into tears of anger, Ritchie raged: "Oh my god, @NatashaOfficial should never be that upset. I'm fuming. I can't stand not being there for her. Farrah your a total b*tch![sic]"
CBB had set the American housemates the secret task and they picked Farrah to wind up the British contestants.
However, after falsely calling Natasha and Gail "lesbians" and using a derogatory word to jibe James, Farrah was hauled to the Diary Room.
Oh my god, @NatashaOfficial should never be that upset. I'm fuming. I can't stand not being there for her. Farrah your a total bitch— Ritchie Neville (@RitchieNeville) September 4, 2015
Big Brother gave Farrah a warning about unacceptable behaviour and she was quick to point out that she only acted in that way for the task. Farrah later apologised to Natasha and the other housemates she had offended.
Before heading into the house, Natasha had revealed that Ritchie was "100 per cent behind her". It appears she was right!
Meanwhile, last night Daniel Baldwin was the first housemate to be evicted, while guest star and former Royal Butler Paul Burrell left the C5 show.
CBB continues tonight (Saturday 5 September) at 10pm.