Her son's battle with cancer has been well documented and now Callie Blackwell has been meeting with supporters during an emotional book signing event at Jarrold department in store in Norwich to share her own experiences.
During a four-and-a-half-year period Deryn Blackwell fought two types of cancer, had four bone marrow transplants and was told he was dying.
Throughout those incredibly tough years, in which Mrs Blackwell had watched her son plan his own funeral and come to terms with his approaching death, there was one thing that kept the family together.
'We dealt with it most of it with a sense of humour if I am honest,' said Mrs Blackwell, who lives in Watton. 'There were times when it was dark but we tried to laugh about it because if you don't laugh you cry.
'We have always been a pretty jovial family and we all try to find the funny side of everything.'
'We saw each other literally every few weeks'
At times Mrs Blackwell and her husband Simon were separated for weeks at a time with one staying with Deryn at a hospital in Bristol while the other remained at home in Norfolk with their other son Dylan.
Mrs Blackwell said their marriage was tested but said their 'strong relationship' pulled them through.
The 37-year-old said: 'We saw each other literally every few weeks. And to keep a marriage going through that you have to be honest. You have to be really brutally honest about anything you're feeling.
'I don't think we would have been able to get through it if we hadn't have had that kind of relationship. You see many families break down through cancer diagnosis.
'We have been incredibly lucky that we just had a strong relationship to start with. We have been very fortunate.'
'Those six months were the hardest six months of the whole thing'
Diagnosed with leukaemia at 10-years-old, Deryn was told 18 months later he had another cancer - Langerhans cell sarcoma - which only five people in the world currently have.
Thought to be the only person to have both conditions at the same time, Deryn - who is now 17 - is a 'boy in seven billion'.
He underwent three failed bone marrow transplants and was told by doctors that a fourth attempt would be his last chance.
But not long after the operation, Deryn got an infection and with no immune system to fight it off, the 13-year-old was given days to live.
He subsequently recovered but it was the time after leaving the hospice, in which Deryn's weight plummeted as he struggled with the uncertainty of whether the cancer would return, Mrs Blackwell describes as the hardest.
'It was very difficult,' she said. 'In fact, those six months were the hardest six months of the whole thing. With the cancer you can deal with that because nobody has any influence in it.
'But when Deryn is point blank refusing to eat anything you've got someone to get frustrated with. There were times when I was on my knees begging him with a cracker in my hand to take just one bite and he'd look at me and just say 'no'.'
Mrs Blackwell said she and her husband struggled to get over what happened to their son.
She said: 'I had a nervous break down and was diagnosed with Post Traumatic Stress Disorder. Both Simon and I struggled with our mental health afterwards because we felt obsolete all of a sudden.
'It was a very difficult time getting our heads around what had happened and that he actually could be well and we could go back to a normal life.'
The future
Deryn completed his GCSEs at Wayland Academy in Watton and now attends a catering course in the hope of becoming a vegan chef and opening his own diner.
Mrs Blackwell added: 'He wants to do things like sky diving and base jumping and bungee jumping. He really looks at adrenaline rushes now. He sees life as very much a-day-to-day thing.
'And if he was to die tomorrow he wouldn't be sad because he fully believes when you're meant to go you're meant to go. And he wants to make sure he enjoys what he can while he is here.'
The book
Callie Blackwell's personal and moving account of her son's physical and mental struggle with cancer is told in her new book The Boy in 7 Billion.
Written with journalist Karen Hockney, Mrs Blackwell said it was 'the right time' to tell her story.
During Deryn's battles, the mother-of-two had been keeping people up-to-date with his progress and now hopes the book will help other families and will give them hope.
She said: 'A lot of people would tell me at the time I needed to put it in a book. So many people were following him and wanted to know how he was doing so again I felt duty bound to continue to let people know. I was able to write a chapter down and shut it and move on.
'I am just a mum who went through what I went through and I decided to tell my story in the hope that other people will gain some hope and just an idea that there is something we can all do to help ourselves.'
Mrs Blackwell met supporters at her book signing event at Jarrold department store in Norwich on Saturday.
Giving her son cannabis
A big talking point in Callie Blackwell's book was her decision to secretly give Deryn cannabis.
MORE - Did cannabis save 13 year old Deryn Blackwell from Watton after he was given just days to live?
Having beaten cancer but after failed bone marrow transplants, Deryn had no immune system and was given days to live.
To help ease his pain and stop him being addicted to the drugs he was being administered, Mrs Blackwell gave him cannabis - an illegal drug in the UK.
She said: 'I really did try everything and I really did beg with the hospital to help us on all occasions and there really wasn't anything else they could do. I was left desperate and willing to try anything and I am glad I did.'
Mrs Blackwell said after giving her son the drug in liquid form she saw he was more relaxed and he no longer wanted the medication. His blood count rose and his immune system recovered.
Mrs Blackwell said she is unsure whether he would have got better without using cannabis.
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