The water rose quickly, he told CNN, and soon came to their neck.
"We were doing well until the water kept going up, and all the appliances went around the house, like the washing machine," said Armstrong, who is a crab fisherman.
His wife, Lynn, was standing on the kitchen cupboards, the only place where "your head would touch the roof," he said. Only their heads were above the water.
After hours of waiting in the flooded rescue house, Armstrong's wife succumbed to hypothermia and slipped under water.
"And then I stayed with her, and she just drowned on me," he said, breaking down.
When the storm finally released its devastating hold in the Bahamas on Tuesday, it was known that seven people had died – all on the Abaco islands, east of Grand Bahama – and officials fear that the death toll will increase dramatically as new reports arrive as that of Armstrong in the light.
"If it went so fast," said Armstrong as he waited for his wife's body to be recovered.
Armstrong said he then "seized the occasion" and swam out to his boat, which was moored nearby.
"I saw that my boat was still there and I swam," he said.
Armstrong said he had lived in Freeport for 58 years and "fought many hurricanes", but he had never seen floods like this.
"Everything I own is gone," said Armstrong. "Every single thing."