Vivienne Pattison from Mediawatch UK said the anticipated book, which is released today, will defend the abusive actions of the main character, a man called Christian Grey.
The original Fifty Shades of Grey book is an erotic romance novel released in 2011 and written by author E L James.
It received criticism for its graphic scenes with elements of violence.
The new book will be similar to the first but this time from the perspective of Christian Grey, who perpetrates the violence.
Vivienne Pattison told Premier it would mean he could justify his actions and validate violence against his partner.
"It is no fiction that real-life women suffer every day at the hands of domestic violence and abuse," she said.
"For such brutality to be considered entertainment, or justifiable because of the abuser's past experiences, wealth or even 'love', is hugely damaging."
She added that making violence 'sexy' had 'significant consequences'.
"The continuation of this series perpetuates the mainstreaming of domestic abuse. It sends the false message that victims can 'fix' violent, controlling partners by being obedient.
"The extended trailer for the film of the first book in the series called it a 'fairy tale'; a misleading description which suggested a simple love story and masked the series' true themes of humiliation, manipulation, abuse and degradation of women.
"The 'fairy tale' is that, in reality, women in relationships such as the one depicted in these books don't end up like Anastasia - they often end up in a woman's shelter, on the run for years, or dead."