The incident went down last August when Casanova and a group of friends sat down at the Good Stuff Diner. The alleged victim, Niya Rucker, says his group included 2 women who were not Casanova's wife ... and she thinks that's why he went off on her.

According to the suit, Niya was shooting an Instagram Live video of her meal ... but Casanova "mistakenly believed" she was recording him and the 2 women. She says the MC instructed one guy in his group to "take whatever action" was necessary to get Niya's phone ... "including physical force."

Niya says the henchman put her in a strangulation grip, grabbed her phone and deleted the video she'd already posted. She also posted a video of the aftermath, showing her mouth and chin bleeding profusely. In the lawsuit, she says she suffered a fractured jaw, damaged teeth, loss of consciousness, a split lip and several other cuts.

Casanova turned himself in to cops the week after the incident and was booked for felony second-degree robbery. He's yet to stand trial.