Amber Heard has told jurors that Johnny Depp slammed her against a wall and wrapped a shirt around her neck during their 2015 honeymoon on the Orient Express.
Heard returned to the witness stand in Virginia where jurors are considering duelling defamation claims by the former spouses.
The pair married in February 2015 and took their honeymoon on the Orient Express train in July of that year after Depp finished filming the fifth Pirates of the Caribbean movie.
Under questioning from her lawyers, Heard said the couple argued about whether Depp should drink during the trip.
She said they had a loving relationship when Depp was sober but that he often turned violent when drinking or using drugs.
In a sleeping car on the train, Heard said, Depp slapped her across the face and repeatedly slammed her body against a wall.
He then took his shirt off and wrapped it around her neck, she told the jury.
“That’s how I woke up the next morning,” Heard said.
“I woke up with it still around my neck and a giant knot on the back of my head.”
The Pirates of the Caribbean star testified earlier that he never hit Heard and argued that she was the abuser in their relationship.
Depp, 58, is suing Heard, 36, for $US50 million ($A73 million), saying she defamed him when she claimed she was a victim of domestic abuse.
Heard has counter-sued for $US100 million, arguing that Depp smeared her by calling her a liar.
In his testimony Depp said Heard at one point threw a vodka bottle that cut off the top of Depp’s right middle finger.
Heard has denied severing Depp’s finger and said she only hit him to defend herself or her sister.
Depp’s lawyers are expected to start their cross-examination of Heard later on Monday.
The legal case hinges on a December 2018 opinion piece Heard authored that appeared in the Washington Post.
The article never mentioned Depp by name but his lawyer told jurors it was clear Heard was referencing him.
The couple’s divorce was finalised in 2017.
Depp, once among Hollywood’s biggest stars, said Heard’s allegations cost him “everything”
A new Pirates movie was put on hold, and Depp was replaced in the Fantastic Beasts film franchise, a Harry Potter spin-off.
Heard’s lawyers have argued that she told the truth and that her opinion was protected free speech under the US constitution’s first amendment.
Closing arguments are scheduled for May 27.
Less than two years ago, Depp lost a libel case against the Sun, a British tabloid that labelled him a “wife beater”.
A London High Court judge ruled he had repeatedly assaulted Heard.
Depp’s lawyers filed the case in Fairfax County, Virginia, because the Washington Post is printed there.
The newspaper is not a defendant.