The couple opened up about their son's battle with cancer on ITV's Lorraine, saying 14-year-old Antonio was diagnosed with Hodgkin lymphoma in September last year.
Speaking about how the family dealt with the teenager's condition, Miriam said they tried to keep their routine as normal as possible.
'We dealt with it by carrying on and trying to keep things as close to the routine that we had beforehand and also being very open,' the mum explained.
'The day that he was told, and I think that probably us telling him is one of the toughest things that we have ever done, the following day he went to school, he stood up and he told everybody "I have cancer".'
'That's the way he dealt with it but other children and other families deal with it in a different way, you have to find your way.'
Nick, who was the leader of the Liberal Democrats between 2007 and 2015, also opened up about how the condition impacted him as a dad.
'You have this almost physical wish to try and take it off your kid and take it yourself,' he admitted.
'You very quickly move from the shock, to trying to support your child as they're battling through this very heavy treatment.'
The politician also detailed how his son was concerned about falling behind at school, despite having to endure very tough treatments.
'His lymphoma was all over his chest and his neck and he gets tested every three months, I think for a couple of years, so there is always a slight spike of anxiety with us every three months but basically he is on the road to recovery.'
'Interestingly the thing he was most concerned about was sort of falling behind his classmates. His anxiety was more about keeping up with his classmates, keeping up at school. So it was very impressive actually.'
Following their difficult experience, the couple are now raising awareness on behalf of charity Bloodwise, who are urging for more research into less toxic treatments for children with cancer.
In a joint article written for the organisation, Nick and Miriam said: 'Like all parents who have a child diagnosed with cancer, our first reaction was an overwhelming, if irrational, wish to take the cancer away from him and take it on ourselves.
'Antonio had four monthly cycles of chemotherapy, undertook a course of very heavy steroids and was prescribed a barrage of medication including antibiotics and pills to tackle nausea.
'At one point his treatment meant he was taking over 20 tablets per day. The side effects that he experienced were what you would expect, including complete hair loss, vomiting and extreme tiredness.
'But by the end, the treatment appears to have had exactly the effect we hoped for: Antonio is free of cancer, and his regular three-monthly checks have detected no return of the disease.'