But, Ruiz strongly denies the allegations ... and is adamant he is actually the victim in the case.

Julia Lemus filed for the domestic violence restraining order in San Diego back on April 6 ... alleging Ruiz "sexually, physically, and psychologically abused me, making me feel like feel like I had to walk on eggshells around him" while they were dating.

The 26-year-old -- who was with Ruiz from 2015 through 2022 -- added that Andy physically and emotionally abused their two children as well.

In the documents, she also accused Ruiz of abusing both alcohol and illicit drugs ... causing her to "fear for my life and safety and the lives and safety of my children."

Lemus described several instances of alleged abuse from Ruiz in her restraining order application ... saying the 33-year-old began to get physical with her in 2019 after he beat Anthony Joshua for the heavyweight title.

"He began grabbing me by my upper arms and physically yanking me in order to move me wherever he wanted me to go," Lemus said in the docs. She added he also began to "jokingly" punch her in her arms and legs, leaving her with bruises. She attached photos of the alleged injuries to her application.

Lemus claims in the docs ... earlier this year, Ruiz purchased several guns in Las Vegas and wanted to show them to her -- but when she became uncomfortable with all the firearms around, she said he "proceeded to point an AK-47 at my face." She claimed in the docs that after she told Ruiz to stop, he "told me to 'shut the f*** up,' and then noted that the guns did not have bullets in them and mocked me by telling me I was being dramatic."

Lemus then said beginning around February 2023, Ruiz began to sexually assault her -- forcing himself onto her on at least six occasions.

A temporary restraining order against Ruiz was granted shortly after the application was filed on April 6. It ordered the pugilist to stay at least 100 yards away from Lemus. It also prohibited him from owning any firearms. The court also ordered Lemus to have sole legal and physical custody of the couple's children ... at least until a court hearing scheduled for Monday.

Ruiz, however, filed a response to Lemus' docs in court on Thursday ... saying he "categorically denies that he ever has abused Julia Lemus or his children."

He said in the docs there "is no just reason to separate Ruiz from his" kids -- while adding Lemus is the one who's been violent in the relationship.

The boxer said in February 2020, Lemus stabbed him with a knife -- and attached a photo of the alleged injuries he suffered in the incident. He also said in April 2020, Lemus "entered my hotel room with a loaded gun in her hand, and screamed, 'everybody get the f*** out of here.'" He alleged in the docs Lemus hit one his friends in the head with the gun during the altercation, and then broke furniture in the room.

Ruiz also said in the court docs Lemus slapped, punched, and grabbed him "on multiple occasions."

"Not once did I ever engage in any physical response to Julia's assault," Ruiz said.

Ruiz also accused Lemus of stealing $250,000 worth of jewelry from him last month ... and said in the docs that he had made a report of the theft with police in San Diego.

We've reached out to Ruiz, a 35-2 fighter who's rumored to be Tyson Fury's next opponent, for comment ... but so far, no word back.