The reality TV star is being sued by her ex, Twin Hector, who claims she would often physically abuse him during their nearly 3 year relationship, when they were living together in Los Angeles.

In the docs, obtained by TMZ, Twin claims Chyna's abuse reached its peak in September 2021, when she violently attacked him while he was sleeping in their bed.

He claims she rained down blows on his face with her closed fists, elbows and knees ... and he says she pinned his arms down with her bodyweight so he was unable to defend himself.

Twin says the alleged attack left him with severe injuries ... including gashes to his face and a swollen shut eye. He included a gruesome pic in the suit.

After that attack, he claims Chyna called her personal physician to the home to treat him, and she still had his blood on her hands when the physician arrived.

Twin claims BC was often abusive during their relationship, claiming it would usually happen when she was drinking or using drugs, and he says she would often try to strangle him and use household objects as weapons ... including wires, furniture, cell phones, and kitchen utensils.

Rob is also referenced in the suit ... he says Rob and other Kardashians testified in court that Blac Chyna "has a propensity for verbal abuse and extreme physical violence toward her domestic partners and others, primarily when she consumes alcohol.”

As we reported ... Rob testified in April 2022 that Blac Chyna beat him at least 5 times during their relationship, alleging she strangled him with a phone cord while she was doing cocaine and drinking. Rob also testified she held a gun to his head.

In the docs, Twin says BC believes she can verbally abuse and physically attack men without repercussion ... and he's suing for more than $10 million in damages.

Twin's attorney, Kirk Edward Schenck, tells TMZ ... "It is a shocking experience for any man to go through — being attacked by a female aggressor in a domestic violence context and knowing they cannot fight back or even defend themselves for fear of being mislabeled (falsely) the de facto aggressor. Every day in America men suffer what are often brutal injuries, but many lack the courage to come forward and protect their legal rights."

He adds, "Our client is willing to stand up and seek protection under California’s Domestic Violence Protection Act — which applies to all genders. He hopes other non-female victims of domestic violent crime will feel free to do the same."

We reached out to Chyna's camp ... so far no word back.