Johnny Depp takes the stand in defamation trial against Amber Heard

Actor Johnny Depp took the witness stand Tuesday in his legal battle against his former wife Amber Heard, whom he accuses of lying about his abusing her during their brief marriage.

Depp is suing Heard for defamation over an essay she wrote for The Washington Post in 2018, in which she said she had become the “public figure representing domestic abuse.” Although the article never mentions Depp by name, his attorneys said it indirectly refers to allegations she made against him during their 2016 divorce.

The trial in Fairfax County, Virginia, is expected to take weeks. A Fairfax judge ruled in 2019 that Depp was within his rights to bring the case there because The Washington Post’s online editions are published through servers in the county.

Depp told the court Tuesday that he was “obsessed with the truth” and, though he argued with his ex-wife, he never hit Heard.

The “Pirates of the Caribbean” actor went further and testified that he had never “struck a woman in my life.”

“Because the news of this accusation had sort of permeated the industry and then made its way through media and social media ... and since I knew that there was no truth to it whatsoever, I felt my responsibility to stand up not only for myself in that instance, but stand up for my children who at the time were 14 and 16,” Depp said.

Throughout the three-hour testimony, Depp talked about his experiences of abuse from his mother, his ascension to fame and his experience with drug and alcohol abuse.

Little time was spent on his relationship with Heard, who he felt was the perfect partner for him at the beginning of their relationship. But Depp said that he began to notice “unusual” reactions from Heard when he broke routine or didn’t want to go to bed at the same time as her.

He detailed one incident in which he took off his boots after work, upsetting Heard, who said that it was her “job” after she had done so every day he returned home from work.

“Then you started to notice other little tidbits and things that come out,” Depp said. “And then within a year, year and a half, she had become this — another person.”

Depp’s lawyers argued in opening statements last week that Heard ruined his reputation by “choosing to lie about him for her own personal benefit.”

Heard’s attorneys pushed back, describing Depp as an alcohol- and substance-dependent abuser who is seeking revenge.

They said in opening statements that Heard’s essay was written to highlight legislation to protect survivors and that it never detailed allegations against Depp.

Depp addressed Heard’s allegations regarding substance abuse, saying he began taking his mother’s “nerve pills” at the age of 11 and proceeded to self-medicate with substances over the years as a coping mechanism for trauma. But he denied ever becoming “out of control” while under the influence.

“When I was with Ms. Heard and her friends and we were all drinking wine and I was smoking marijuana, they used to tease me because of what they sort of said was a ludicrous tolerance,” Depp said. “Because I’ve never appeared loaded or high or any of that ... no one would have ever known.”

Depp also admitted to being addicted to an opiate he was prescribed after injuring himself on the set of the fourth “Pirates of the Caribbean” film. He said he detoxed from the drug prior to his relationship with Heard.

He accused Heard of using his history with substance abuse against him because it was an “easy target.”

“Once you’ve trusted somebody for a certain amount of years and you’ve told them all the secrets of your life, that information then of course can be used against you ... I am not some maniac who needs to be high or loaded all the time,” Depp said.

Depp’s testimony ended at about 5 p.m. ET, and he is expected to be cross-examined by Heard’s attorneys Wednesday.

Their former couples therapist, Laurel Anderson, testified that the abuse appeared to be “mutual” during their marriage. Anderson said Depp told her that Heard “gave as good as she got.”

Heard would rather be in a fight with Depp than see him leave, and she “would strike him to keep him there,” Anderson said. During cross-examination, Anderson clarified that her understanding was that Heard “fought back” after Depp became physical.

In court filings before the trial, Heard said she hit Depp only in self-defense or in defense of her younger sister, according to The New York Times.

Anderson also testified that Heard, in a session conducted separately from her husband, said Depp hit her and that she showed her bruises.

Heard was granted a protective order in May 2016 after she alleged that Depp hit her in the face with a cellphone. She presented evidence to the court — a photo of a bruise to her face — and claimed he pulled her hair, screamed at her and hit her repeatedly.

“During the entirety of our relationship, Johnny Depp has been verbally and physically abusive to me,” Heard said in a sworn declaration at the time.

She also said she lived in fear of Depp, saying he had a “short fuse” and terrorized her.

Depp, the star of the “Pirates of the Caribbean” movies, denies having ever physically abused Heard. It is his second attempt to sue over the allegation; a libel suit in the United Kingdom failed two years ago.

Depp sued News Group Newspapers, which publishes The Sun, for calling him a “wife beater” in a 2018 article about the couple.

Justice Andrew Nicol ruled against Depp, saying the British tabloid had presented substantial evidence to show that Depp was violent against Heard on at least 14 occasions.

Depp’s attorneys said Nicol relied too much on Heard’s testimony, describing her as an unreliable witness and a compulsive liar.

This story first appeared on NBCNews.com.