Pua's twin Tanu learned of it first and rang Robbie in the early hours of May 11, but as the eldest sibling it fell to Robbie to deliver the tragic news to their father, Ropati, 70, and their mother, Salafa, 68.
"When Dad answered, he was all chipper, and then I had to tell him and he started wailing," Robbie Magasiva told Woman's Day. "I'd never heard that before."
Magasiva - who recently got two tattoos in memory of Pua, affectionately known as "Poos" - told the magazine that Pua had been having a difficult time since the middle of last year, when his role as nurse Vinnie Kruse on Shortland Street came to an end.
Soon after, Pua resigned from his job as breakfast host on Flava.
That came in the wake of a drink driving charge in November 2017, which led to a suspension of his license that he later breached.
Magasiva told Woman's Day that he now wondered if he has missed some indicators as to Pua's mental health the last time he saw his brother alive in April.
"I guess if any good comes out of Pua's death, I urge you to surround yourselves with people you trust and check on your mates," he said.
He added that the family, comprising Ropati, Salafa and Tanu as well as two other brothers, Steve and Miki, and sister Trina, were focusing on supporting Pua's eight-year-old daughter.
"To be honest, life will never be the same for us," he said.