The 33-year-old is preparing to enter the I'm a Celebrity jungle tomorrow night.
But just days before she flew out to Australia it was alleged that she and her ex got into an argument and she called the police.
The Sun reported today that he handed himself into the police, and he is now being questioned on suspicion of causing actual bodily harm.
Police confirmed a man has been released on bail until January.
It was claimed that their argument last week left Gemma with injuries.
Gemma and her ex first got together when she was in her early 20s, but it is reported he was later jailed for conspiracy to supply cocaine.
GEMMA COLLINS 'LOOKING TO LOSE WEIGHT' IN THE I'M A CELEBRITY JUNGLE
They are said to have rekindled their relationship when he was released in August.
At the time of the alleged assault police confirmed: "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."