The 33-year-old was preparing to fly out to Australia for this year's I'm a Celebrity, Get Me Out Of Here when Alexander Moss is said to have assaulted her.
A source close to Gemma told the Mirror: "Gemma was gearing up to fly to the jungle when the incident happened. She was preparing to go to the jungle as a single girl. But she had an argument with Alex and flew off the handle.
"She is not in a good way and has been badly hurt and her house has been smashed up. The police were called."
Gemma was supposed to be filming TOWIE's series finale yesterday, but it is unclear whether she made it. However she is still expected to go to Australia this week.
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She and Alexander first got together when she was in her early 20s, but he was jailed for five-and-a-half years in 2012.
Upon his release in August this year, he and Gemma rekindled their relationship. The source continued: "Gemma had given Alex a second chance and he had convinced her he was a reformed character – she really believed that he had changed."
Writing in her autobiography Basically… My Life As A Real Essex Girl, Gemma described him as a "bit of gangster but with a big heart."
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Police confirmed last night: "We were called to an address in Warley near Brentwood shortly before 1.15am today following reports a woman had been assaulted.
"Officers went to the location and the victim was assessed by ambulance paramedics but did not need hospital treatment.
"Police inquiries into the incident are continuing, a potential suspect has been identified and is being sought by police."