Mrs Mills, from Chertsey, Surrey, is convinced that his death aged 51 was caused by radiation from the mobile phone he used for work. She is suing Motorola, the manufacturers, for failing to warn him about the health risks.
Mrs Mills is one of more than 20 people in Britain preparing lawsuits against mobile phone manufacturers, as reported in the Independent on Sunday last week. They could cost the industry billions of pounds in compensation.
She says her husband neither smoked nor drank alcohol and had always been healthy. Last Christmas he noticed a lump on his neck in the place where he held his mobile phone.
Mr Mills had been a BT engineer for eight years. He often had to put his head inside steel junction boxes while he talked on his mobile for considerable periods of time.
"He was never in hospital since the day he was born," said Mrs Mills. "His diet was good and he'd even stopped eating beef. He used to have a pager for work, but about a year ago, he came home and said everyone had been issued with mobile phones.
"My husband used to put up phone lines and spent a lot of time talking to head office as he checked wires. He could be in the queuing system for a long time waiting to talk to someone as he worked in confined spaces. He would have his phone held in the crook of his neck so he could be working at the same time. From the time he got ill, he thought it was the phone. Only six months after the phone was issued, the lump developed and it grew to the size of a grapefruit.
"He was put on two types of antibiotics which did not work, then had to go for chemotherapy. He swelled up like the Michelin man. It was horrendous seeing him suffer like that. Towards the end, he couldn't stand or speak because his windpipe was pushed to one side."
Mrs Mills is angry that manufacturers did not issue health warnings which could have saved her husband's life.
"No one wants to know because the industry is worth so much money. I don't blame BT, because no one knew about the risks at the time. It's the mobile phone companies I blame, because they knew but were too greedy to do anything."
"There should be warnings on the phones, like on cigarette packets, saying they can kill you. I was married for 24 years to the only man I ever loved. Now I'm living in a void."
George Howard (not his real name) also developed cancer after using his mobile phone. The company director from Middlesex is suing Motorola through solicitors Leigh Day. Mr Howard, who has used a mobile for nine years, first started to experience headaches two years ago and then discovered a lump where he held the telephone to his ear.
Doctors have removed two tumours from his head and plan to operate on a third which has developed on his brain stem. He also suffered temporary blindness as a result of the tumour.
The company director, who now uses a radiation shield on his phone, says he was never informed of any health risks by the manufacturers.
"I was making four to five calls in one go and was probably speaking on it for about half an hour a day. When I started to get headaches, I didn't think there was a link so I carried on using the phone," he said.
"But the cancer I have is very rare and there is nothing in the family like this. There is no reason for me to develop cancer apart from the link with the phone. I don't drink or smoke and have a healthy diet.
"There is now always the thought in my mind whether other tumours are going to develop and it was very frightening when I went blind.
"I think the risks, however small they may be, should be made public. Instead, the manufacturers seem to be reacting after the event."
Paul Betts, a 36-year-old mechanic from Watford, in Hertfordshire, now uses a hands-free phone attachment after experiencing a burning sensation in his ear. His health problems became apparent soon after he got a new phone: "When I used the phone it was like someone was sticking a finger in my ear. I've now restricted my use of the phone dramatically. The companies should make you aware of the risks.
"I smoke like a trooper and drive like Nigel Mansell but I know what the risks are. The phones are like microwave ovens - they cook from the inside out. I certainly don't think they are safe to use for a long duration."