Gareth Thomas said one of his family members has died from coronavirus.
The ex-Wales captain disclosed the information during an interview on BBC Radio 5 Live.
He also said he is "petrified" for his daughter, who works in the NHS.
On Tuesday 7, the number of coronavirus deaths in Wales rose to 212.
The former Wales international announced how he and his family had been personally affected by the virus so that people would "see the reality" of what is happening.
The sports star is married to Stephen Thomas, who it is believed has a daughter who works in the NHS.
Thomas also spoke of his disgust at online abuse directed at Boris Johnson.
The Prime Minister is in hospital being treated for coronavirus. He was moved to intensive care on Monday.
Thomas said he could not "believe the hatred" behind some of the comments, which included death wishes.
Health Minister Vaughan Gething has confirmed three more testing centres will be built around the country as the Welsh Government aims to meet its target of 9,000 coronavirus tests a day by the end of April.
A testing centre at Cardiff City Stadium has been erected and will prioritise healthcare workers.