Giving evidence from the UK on Tuesday, actor Kristian Lavercombe, 46, described how he kept McLachlan company on the evening that reports from the ABC and Fairfax were published in January 2018, saying he was "on a bit of a suicide watch".
"He seemed to have aged about 30 years overnight. He looked very frail and yeah he was kind of in shock," Lavercombe told the NSW Supreme Court.
McLachlan's wife and conductor, Vanessa Scammell, also returned to the stand and faced heated questioning by defence barrister Michael Hodge QC.
Mr Hodge accused Scammell of fabricating evidence and exaggerating the number of times she had attended The Rocky Horror Show in an attempt to bolster her husband's denials of the reported allegations.
"The reason that you're making this up is to try to protect Mr McLachlan," the barrister asked.
"No," said Scammell after a long pause.
Scammell had claimed she was in McLachlan's dressing room on a night he admitted kissing actress Erika Heynatz to dispel any notion that her husband was romantically involved with another woman, Mr Hodge suggested.
While giving evidence she had been in attendance in her husband's dressing room for "90 to 95 per cent" of the show's Melbourne run, the jury was shown texts from Scammell to Whelan Browne in June 2014 saying she had "hardly been" to the theatre at the time.
An angry Scammell interrupted Mr Hodge at one stage during questioning, rejecting the barrister's suggestions she had lied about being at the theatre when a feud between Whelan Browne and Heynatz over who got a larger dressing room "blew up".
She said she did not believe the media reports against her husband, but admitted she would be hurt if the allegations within them were true.
"If he had done the things he's accused of, would you regard those things as a betrayal of you?" Mr Hodge asked.
"Yes," Scammell replied.
She rejected suggestions by Mr Hodge that she felt justified in lying for her husband because she felt that the Rocky Horror actresses had lied about him to the media.
Lavercombe also testified about how Rocky Horror cast member Christie Whelan Browne, who accused McLachlan of commenting on her white knickers and "slit" in 2014, teased other cast members about their talent and appearance at the time.
Lavercombe said Whelan Browne and McLachlan had a similar sense of humour and would often play pranks by "goosing" each other. This meant pinching someone else's buttocks, the actor explained.
Whelan Browne was accused of "running down" Heynatz during the dressing room spat by saying she looked like a "tranny" and had "man-hands".
"Erika's quite tall so she was always insinuating she looked like a man, but saying it as a joke," Lavercombe said.
Lavercombe said Whelan Browne had also made fun of another actress, saying she wasn't talented enough to play the main role of Janet in The Rocky Horror Show. This other actress, who cannot be named, played Janet while Whelan Browne took time off during the 2014 run.
McLachlan, 56, is suing the ABC, Fairfax and Whelan Browne for defamation over two articles published in January 2018 which accuse the actor of touching, kissing and groping actresses without permission in The Rocky Horror Show, Neighbours, City Homicide, and The Doctor Blake Mysteries.
The hearing resumes on Wednesday.
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