Johnny Depp has told the high court that he lost $650m he made at the height of his Pirates of the Caribbean fame and was left owing $100m in taxes on account of business managers whom he accused of stealing from him.

On his final day of evidence in his libel case against the Sun, the actor denied he had been violent towards his ex-wife Amber Heard.

The court heard more about the backdrop to one alleged incident in which Depp turned up late to Heard’s 30th birthday party in 2016 after receiving bad news at a meeting about his finances. She alleged he later threw a magnum of champagne at her and pulled her hair.

Under examination from his barrister, Depp told the court: “I was in the early stages of learning from my recently acquired new business manager that the former business managers had taken quite a lot of my money. They stole my money.”

Pressed to say how much money was allegedly taken, he replied: “It was put to me this way, because I had no idea about money or amounts of money. Since Pirates [of the Caribbean] 2 and 3, I had – and this is ludicrous to have to state, it’s quite embarrassing – apparently I had made $650m, and when I sacked them, for the right reasons, I had not only lost $650m, but I was $100m in the hole because they [the previous business managers] had not paid the government my taxes for 17 years.”

Depp is suing the Sun’s publisher, News Group Newspapers (NGN), and its executive editor, Dan Wootton, over an article that called the actor a “wife beater” and referred to “overwhelming evidence” that he had attacked Heard.

At another stage in the evidence, Depp simulated the act of punching in order to demonstrate what a “haymaker” was. The term had been used by him in what he had regarded as a “secret recording” during a meeting with Heard in San Francisco in July 2016, when he could be heard to say “you fucking haymakered me, man”.

Depp’s barrister, David Sherborne, asked what a haymaker was, to which he replied: “It’s just a type of wild swinging … kind of a roundhouse punch, as it were. It’s a bit of a wild swing, but effective if it reaches the target.”

The court was shown a photo of the actor passed out and covered in ice-cream, which the court was told Heard had shown to her then husband in 2014 to “show how pathetic” he had become.

It came up as Sherborne reminded his client that Heard had said she would take photos to be able to show Depp what he had done because he would not remember the next day.

Asked if he had seen the photos in the past, Depp said there was one that his ex-wife had shown him, which was of him on a flight from Boston, at a time when he had been working 17-hour days, and he had already agreed he was going to go to the Bahamas to detox.

He added: “I was obviously on the nod and very tired, falling asleep, and the ice-cream then spilled all over my leg and then she took that … and showed me the next day and said: ‘Look at what you’ve become … look at you, it’s pathetic.’”

Earlier in the day, the court was told that Depp could not, as alleged by Heard, had grabbed her by the hair with one hand and hit her “repeatedly in the head with the other”, because he had been wearing a cast on his finger after an incident in which he lost the top of his middle finger in Australia.

The case also heard evidence from Depp’s former personal assistant Stephen Deuters, who alleged in a witness statement that Heard subjected Depp to “years of abuse”.

Deuters, who worked as a PA to the actor for 16 years and went on to hold the role of European president of his production company, also said in the statement that he was “extremely surprised and outraged” when it became public that she had filed for a temporary restraining order against Depp.

Deuters described Heard as “sociopathic” and a “machiavellian overlord”. When asked by Sasha Wass QC, representing NGN, how he felt when Depp and Heard split up, he agreed that he would have been relieved.

Wass read out a text from Deuters to Depp’s friend Paul Bettany on 26 May 2016, which stated: “That moment when everything comes home to roost and all the shit compounds itself into one monstrous steaming pile of catastrophe. Just trying to keep him upright at the moment. But at least the bitch is gone. Yes, I do mean Amber – not the mom.”

The next message by Deuters, apparently describing Heard, read: “Sociopathic show pony. Machiavellian overlord. Talentless cunt. Good riddance to bad shit. Yes, I do mean Amber not the mom, even though she was a devil herself.”

Wass asked Deuters about a private plane flight from Boston in May 2014, when Heard alleges Depp threw objects at her, slapped her and kicked her in the back before passing out in the toilet.

Deuters said he recalled a foot being raised, adding that “it was quite a feat for anyone really” on account of the tight layout of the aircraft’s furniture.

Deuters, who has said in a statement that Depp had sought to “playfully tap her on the bottom with his foot”, told the court he had a clear view of the incident and Heard was “very upset”.

When it was put to him that he and other assistants, as Heard alleges, “did nothing” to help her on the flight, Deuters said: “I remember that we got up from the seats in order to intervene. It had clearly reached the point where we wanted to help or stop or intervene.”

He said he could not recall Depp being violent towards Heard during the flight.

The flight is one of 14 alleged incidents of domestic violence that NGN is presenting in its defence against the actor’s libel claim. Depp denies all the allegations.