, Billy's family said he developed mild symptoms on 16 November - but seemed like he was going to be fine.
Sonya said: "He would have a fever at night, but not all day long. For a week he actually seemed OK. But, it just turned quickly south from one moment to the next."
He wrote this email to her before he was put on a ventilator Credit: Facebook / Sonya Kypuros Billy sadly passed away on 13 December Credit: Facebook / Sonya Kypuros 10 days later, Billy woke up struggling to breathe - and Sonya rushed him to hospital.
She recalled: "For two weeks he was just trying really hard. He was trying his hardest to not be put on a ventilator.
"I kept telling him that he would be OK, that he would get through this and that he would come back to me.
"It's just awful that I couldn't be there to hold his hand, and that he was fighting there for his life by himself."
Billy urged his wife to live her life with 'no regrets' Credit: Facebook / Sonya Kypuros Although Billy had no underlying health problems, his condition continued to deteriorate - and doctors were forced to put him on a ventilator.
Aware that he might not survive the virus, Billy wrote this heartbreaking letter to Sonya: "I want you to know that I am fighting very hard every day for my life. I do it for you so that I can see you again. You are the most important person in my life and I miss you everyday."
"I know I am not always the perfect man I want to be, but I do my best. You, for me, have always been perfect, even when I say you are not and I get mad. 99% of the time I am wrong and you are right and I love that.
"If I make it through this I promise to be a better man, in God, in life, and as a husband. You have always deserved the best and I get a second chance I will do it.
He thanked Sonya for a 'happy wonderful life' which he wouldn't have traded for 'all the riches in the world' Credit: Facebook / Sonya Kypuros "If I don't make it, I want you to know that I lived a happy wonderful life with you and would never have traded it for all the riches in the world.
"I also want you to be happy and continue to live your life without me and with no regrets. We had our time and it was wonderful. I love you and miss you very much. I will keep fighting. Love, Billy."
Speaking to Good Morning America, Billy's brother Peter said Sonya knew in that moment that this would be the last letter she ever received from her husband.
"It's bittersweet," he said. "She got to receive her last love letter from my little brother and that breaks her heart in pieces."
Billy's letter to Sonya:
I want you to know that I am fighting very hard every day for my life.I do it for you so that I can see you again. You are the most important person in my life and I miss you everyday."
I know I am not always the perfect man I want to be, but I do my best. You, for me, have always been perfect, even when I say you are not and I get mad. 99% of the time I am wrong and you are right and I love that.
If I make it through this I promise to be a better man, in God, in life, and as a husband. You have always deserved the best and I get a second chance I will do it.
If I don't make it, I want you to know that I lived a happy wonderful life with you and would never have traded it for all the riches in the world.
I also want you to be happy and continue to live your life without me and with no regrets. We had our time and it was wonderful. I love you and miss you very much. I will keep fighting.
Love, Billy.
Billy sadly passed away on 13 December - less than one month after he contracted coronavirus.
"I think he was trying to give me permission to be happy without him," Sonya added. "That was hard to read. But he took care of me and took care of everyone so I'm not surprised he wrote that."
Sonya has shared her husband's final letter in the hope it'll act as a reminder of how dangerous the virus still is.
She said: "Be mindful of who you could get it from or who you could give this to."
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