Amber Heard’s former personal assistant has accused the actor of stealing her own experience of being a victim of sexual violence and twisting it into a different story.

In evidence given remotely from Los Angeles, Kate James also said she had regularly received a barrage of drunken, abusive and incoherent text messages from Heard between 2am and 4am.

James was answering questions during the libel trial brought by Heard’s ex-husband Johnny Depp, 57, who is suing the Sun’s publisher, News Group Newspapers (NGN), and its executive editor Dan Wootton over an article that called Depp a “wife beater” and referred to “overwhelming evidence” that he had attacked Heard.

Depp denies ever hitting Heard, 34, who has submitted details of 14 occasions during their relationship when she claims he assaulted her. The paper has to prove the allegations are substantially true.

In her second witness statement to the court, James said she had been the victim of rape in Brazil when she was in her twenties and that the experience had “haunted” her ever since.

When she read Heard’s submissions, James said, “to my utter shock and dismay, I discovered that Ms Heard had in fact stolen my sexual violence conversation with her and twisted it into her own story to benefit herself. This of course caused me extreme distress and outrage that she would dare to attempt to use the most harrowing experience of my life as her own narrative.”

James told the court that although she had been subpoenaed to give evidence, she was doing so because she is “a sexual violence survivor and it’s a very serious to take that stance if you are not one”. At that point Sashsa Wass, QC, representing The Sun, abandoned her cross-examination of James.

Referring to Heard’s drinking habits, James said in a witness statement: “Amber would drink vast quantities of red wine each night.”

In court, questioned by Depp’s counsel David Sherborne, James added: “I would receive a barrage of drunken text messages between 2am and 4am that were incoherent and abusive.”

In a final comment, James said Heard was “probably the least known person” she had been employed by in Hollywood.

Earlier the court was told by Depp’s former butler that Heard often drank a bottle or two of wine a night when she was with Depp, and she was the “antagoniser” in the relationship.

Ben King, who looked after homes where the couple stayed in London, Australia and Vancouver, said he had, however, noticed on one occasion what he thought were cuts on her arm, when they returned to Los Angeles.

King, who gave a second statement for the trial at the beginning of this week, said he had been told when interviewed for the job “that Mr Depp was teetotal, having been a drinker”.

He told the court the only drug he had seen the Pirates of the Caribbean star take was cannabis. “He seemed to smoke cannabis sometimes around the house.” He also said Depp was “always polite”.

In his first statement, King, whose role was described as house manager or butler, said: “I frequently witnessed Ms Heard goading and attempting to provoke Mr Depp. I never witnessed Mr Depp be violent or unkind towards Ms Heard or indeed anyone else.”

King said he had not seen Depp drink during their stay in London. “It was Ms Heard who was drinking the wine,” King said. “I believe she would regularly drink at least one or two bottles a night. I made a tally of the bottles of wine left on the counter or in the bins when I arrived each morning. I was usually the first one there. I would often see Ms Heard drinking wine.”

When the couple were in Australia – where the court has heard they clashed and the house they were staying in was wrecked – Heard would “harangue Mr Depp during the arguments, which seemed worse than they had been in London”, King said.

On the flight back from Australia, King said in his second statement: “I did notice on one arm that she had a couple of marks which … looked like cuts in fairly uniform lines at a sort of diagonal angle downwards.

“I recall saying to her when we landed [in Los Angeles] that she may want to put her sleeve down as there might be paparazzi in the airport … She did not refuse but she chose not to.”

During the same flight, King said, Heard turned to him and asked: “Have you ever been so angry with someone that you just lost it?” He said he had not.

Kevin Murphy, Depp’s estate manager, giving evidence by video link from the US, told the court that Heard had threatened him with losing his job if he did not perjure himself and make a false statement about the couple taking their pet dogs into Australia without having the correct vaccines.

The issue of the arrival of the two dogs, Pistol and Boo, in Australia in April 2015 turned into an international media furore after Depp was told he could face up to 10 years in prison for bringing them without the correct health certificates.

Murphy admitted he had signed a declaration for the courts in Australia that “contained statements that were not entirely true” and said it was because he had been threatened with losing his job by Heard.

“Amber wielded a lot of power and might make my life miserable,” Murphy told the court.

The hearing at the high court in London continues.