Mr Clarke also said while there were several elements that contributed to his wife's death, the certificate indicates it was severe bilateral pneumonia that was the primary cause.
Infectious diseases expert at Sydney University Robert Booy told the Daily Telegraph: "Lupus can weaken the lungs directly, so they may have already been damaged, increasing the risk of pneumonia and infections".
'That's not something I ever envisaged doing, that image is now in my mind'.
"Me and Kelly have been through a lot, [she's] been there for me, been my star".
"We just want her home, it's a waiting game for us now, we're just shocked and devastated and can't explain how we feel".
The family received a death certificate for Mrs Clarke from Fiji authorities on Sunday after an autopsy was undertaken.
"She said call an ambulance".
She was placed into an induced coma and was reportedly in a very unstable condition. The cost to get the young woman's body home is expected to be over $60,000 and will be covered by a combination of insurance and funds from the Department of Foreign Affairs.
Her husband Chase Clarke told Fairfax radio she was "outspoken, smart, courageous, and had the biggest heart".
"This whole situation should never have happened".
"She told me she was scared she was going to die", he said.
"I told her to be strong, that I was coming straight back and to rest up because she needed her strength".
Mr Clarke said his wife was intelligent and loving.
Ms Clarke, a recently-graduated registered nurse at The Children's Hospital at Westmead, initially complained of stomach pain.
"Kelly was bright, bubbly and over the top; she loved her makeup and always looked the part", Kirribilli Club duty manager Launa Harper said.
'She went into cardiac arrest five times in the last hour and the medivac team didn't make it in time. 'You attractive girl and fantastic sister you will be deeply missed'.
Mrs Clarke's sister Tam Brown started a fundraiser to bring her home to pay for emergency treatment raising $50,000.
Our thoughts are with her family at this heartbreaking time.