Earlier, Ms Heard insisted she was “never violent” towards Johnny Depp and does not have a problem with her temper.
The Aquaman actress claimed her ex-husband often put her in situations where she was “confronted with unimaginable frustrations and difficulties”, adding she would “try to defend” herself when he “got serious”.
Ms Heard has also denied allegations that she was often the one to start arguments with the Hollywood star.
And she has alleged that she was afraid Mr Depp was going to kill her at points in their relationship.
Ms Heard, 34, is giving her first of three days of evidence at the Royal Courts of Justice in London, as part of Mr Depp’s libel case against The Sun newspaper over a 2018 article that labelled him a “wife beater”.
Eleanor Laws QC, representing Mr Depp, asked Ms Heard if she ever “got violent” with Mr Depp, to which the actress said: “No, Johnny often put me in a situation where I was confronted with unimaginable frustrations and difficulties, often that were life-threatening to me.”
She added that she would “try to defend myself when he got serious and when I thought my life was threatened, but I was never violent towards him.
“When I felt my life was threatened, I tried to defend myself and that started to happen years into the relationship, years into the violence.
“Before that, I didn’t even try to defend myself, I just checked out.”
The court heard a recording of a conversation between Ms Heard and Mr Depp, in which Mr Depp can be heard to say: “I’m not the one who throws pots and whatever the f*** else at me.”
Heard told the court: “That’s different. That’s different … that’s irrelevant, that’s a complete non sequitur.”
Ms Laws went on to say: “You were admitting throwing things at him but not in the context of self-defence. It sounds as if you are admitting throwing pots and pans.”
Ms Heard replied: “It might sound like that to you, but because I lived it I can explain to you… (it is) not what it sounds like.”
She also said she threw things “only to escape him”, adding: “I’m not admitting throwing pots and pans, I’m trying to keep Johnny on track in this argument or in this conversation.”
Ms Laws also asked Ms Heard if she has “a problem with controlling your temper”, to which the actress said she did not.
The barrister then suggested: “You would have outbursts of rage and anger.”
Ms Heard replied: “I did have outbursts of anger at times and there were times when, yes, I lost my cool with Johnny in our fights, in our arguments.”
Ms Laws referred to “a number of witnesses” who had described Ms Heard as “being the person who would start an argument with Mr Depp… you would be the one to start the argument, do you agree with that?”
Ms Heard said: “No… they didn’t see our arguments, his employees didn’t see our arguments. These things happened behind closed doors.”
In a written witness statement Ms Heard has said Mr Depp, 57, threatened to kill her “many times”, especially later in their relationship.
She accused Mr Depp of subjecting her to verbal and physical abuse – including screaming, swearing, issuing threats, punching, slapping, kicking, head-butting and choking her, as well as “extremely controlling and intimidating behaviour”.
Ms Heard alleged: “Some incidents were so severe that I was afraid he was going to kill me, either intentionally or just by losing control and going too far.
“He explicitly threatened to kill me many times, especially later in our relationship.”
Ms Heard said Mr Depp has a “unique ability to use his charisma to convey a certain impression of reality”.
“He is very good at manipulating people,” she said in her statement.
She added: “He would blame all his actions on a self-created third party instead of himself, which he often called ‘the monster’.
“He would speak about it as if it was another person or personality and not him doing all these things.”
Ms Heard is facing questioning over 14 allegations of domestic violence – all denied by Mr Depp – which The Sun’s publisher, News Group Newspapers (NGN) relies on in defence of the April 2018 article.
The court has so far heard nine days of evidence about Mr Depp’s Hollywood lifestyle, his use of drink and drugs and his attitudes towards women, as well as his and Ms Heard’s volatile relationship – described by Mr Depp as “a crime scene waiting to happen”.
Mr Depp and Ms Heard met on the 2011 film The Rum Diary and began living together in 2012 before marrying in Los Angeles in February 2015.
Mr Depp is suing NGN and executive editor Dan Wootton over the publication of an article on April 27 2018 with the headline: “Gone Potty: How can JK Rowling be ‘genuinely happy’ casting wife beater Johnny Depp in the new Fantastic Beasts film?”
His lawyers say the article bore the meaning there was “overwhelming evidence” Mr Depp assaulted Ms Heard on a number of occasions and left her “in fear for her life”.
NGN is defending the article as true, and says Mr Depp was “controlling and verbally and physically abusive towards Ms Heard, particularly when he was under the influence of alcohol and/or drugs”.
Mr Depp is suing Ms Heard in separate libel proceedings in the US over a December 2018 column in the Washington Post, which did not mention Mr Depp by name, but said the actress received “the full force of our culture’s wrath for women who speak out”.