Baldwin said their dinner was to advise her on forging a mainstream acting career and was nothing more than a "favour" to Bregman, who was allegedly desperate to be rid of his on-off girlfriend.
Baldwin denies sleeping with her but says he drove her back to the swanky Lowell Hotel, where he had helped her get a reservation.
He claims he never saw her again until she turned up uninvited at his East Hampton, Long Island home on March 31, 2012, the afternoon that he got engaged to his second wife Hilaria.
Wearing a navy blazer and a black polo shirt, Baldwin testified for just under two hours.
He insisted he knew Sabourin purely in a professional context and that their subsequent email contact had been nothing more than him trying to be "polite" and shake her off.
But an angry and emotional Sabourin, dressed in a figure-hugging black and cream jumper, skin-tight black trousers and knee-high black suede boots, repeatedly interrupted Baldwin's testimony.
She called him a liar, shook her head, laughed and mocked him, provoking Judge Robert Mandelbaum to repeatedly demand, then to shout at her, to be quiet or be held in contempt.
"Don't testify from your seat at the defence table while the witness is on the stand," Mandelbaum told her.
"Your honour, he's lying," Sabourin replied.
"Do you want to speak to your client before I have her removed from the courtroom?" the judge asked Sabourin's lawyer.
At one point, Sabourin and her lawyer briefly left the courtroom, but after they returned she continued to disrupt proceedings.
When Baldwin accused her of behaving like an alcoholic, a drug addict or someone having a breakdown, Sabourin again protested saying: "This is vilifying me in the press."
Baldwin said Sabourin left "hundreds and hundreds" of messages that would vary "wildly" between her sobbing and begging to be called, to laughing with plans for what they could do together.
Her appearance at his Long Island home, at a film event he co-hosted on April 5, 2012 and once at his New York apartment made him feel "extremely, extremely threatened" and scared for his wife, he said.
Asked to recount events on March 31, Baldwin sighed, looked down, pursed his lips and said "I'm sorry" as if distressed.
He then wiped his eye, provoking an indignant Sabourin to shout: "Why is he crying?"
The defence tried to take Baldwin to task over his reputation for anger, including a notorious message in 2007 for his then 11-year-old daughter calling her a "rude, thoughtless little pig".
But the actor kept his cool and was combative, often replying that he could not recall and telling the defence lawyer to speak more slowly, saying: "I know you're nervous."
The defence sought to establish that Baldwin exchanged emails with Sabourin during 2011 and 2012 in a manner that suggested something other than a purely professional contact.
Baldwin admitted to offering her advice on how to move on, but that he thought being patient would help her go away.
Hilaria, 29, also took the stand, saying how she had become "terrified" of Sabourin after starting to date Baldwin in 2011.
Dressed in a grey knee-length dress and black cardigan, she told how Sabourin shrieked "You bitch, you bitch, you bitch" at her on the phone in around May 2011.
Sabourin interrupted Hilaria - shouting "She's going to hell" - and earning yet another rebuke from the judge.
At the April 2012 film event, Hilaria told how she was taken to a locked room for her safety but that Sabourin later ran towards her in the auditorium.
"I've never been more afraid in my entire life," she said.
A few days later, Sabourin turned up in the lobby of their Greenwich Village apartment building on Easter Sunday and she dialed the police, Hilaria said.
The case continues.
- AFP
