Model, actress and radio personality Pearl Thusi was in a car accident that left her and her daughte.
Tau's shock announcement follows his failure to secure an extended stay at Chiefs after a lengthy ankle injury that kept him out for most of last season.
Tau was skipper at Amakhosi, a club he joined from Soweto rivals Orlando Pirates, where he was also captain during his eight-year spell.
Chiefs clinched the Absa Premiership for the first time since 2005 in coach Stuart Baxter's first campaign last season, but despite getting a winners medal, Tau did not play a single match.
"I believe I served with loyalty and pride," said the defender, who began yesterday's press conference by quoting a Bible verse.
"My opinion about what happened [at Chiefs] will count when I write my book, which I expect to release in December as a Christmas gift. I am excited about that."
Tau, who turned 33 on the day he announced his retirement, refused to say whether he would have continued playing had Chiefs offered him a new deal. He also reiterated that the reasons why Amakhosi pushed him out were not football-related.
"It is difficult for me to answer an 'if' question. But I have recovered from the injury that kept me out during the season. That struggle is over. I've never been injured for so long, but I still believe my future is still bright," said Tau.
Last week, Chiefs team manager Bobby Motaung said in Tau's absence at right back, the club had managed to secure replacements ahead of their title-winning season and there was simply no room for the former Bafana player when his contract expired.
Tau confirmed that he could have joined other clubs in the Premier League as he had numerous suitors, however, he decided it was the right time to "hang up my boots".
"There are plenty of opportunities for me and I have decided to focus on myself as a brand.
"Playing for Chiefs and Pirates has helped and I feel it is the right time to leverage that," he said.