When my mum was diagnosed with late-stage cancer she turned to me and said, 'We will get through it.' At the time, I did not know what that could possibly mean.

Looking after my mum disrupted my normal life. Being her carer took away my time. It made me lose interest in music and endangered professional opportunities. It also dragged my pregnant wife and young son into a world of commodes, hoists, medication and round-the-clock worry.

But amidst the difficulties we all built our motivation on one solid belief, that life was something precious, something to be celebrated, cherished and affirmed. As mum's health declined and the opportunities for 'normal life' decreased, the possibilities expanded. We lived the paradox that when there are limits to life the freedom is greater. Mum knew that positive experiences would sustain the bereaved left behind: that further altruism gave her life some meaning.

I am so glad I did not have to discuss the Assisted Dying Bill with my terminally ill mother. I think that if my mum had lived to know about this Bill it might well have destroyed all our happy experiences. I think she would have been terrified to know that the same doctors so keen to see her enjoying life, even in a limited way, might be perfectly willing to help her to end her life, should she have so chosen. It would have destroyed the relationship of trust to know that there were no boundaries between healthcare professionals and patients. And it would have demoralised her carers, who together worked towards making life comfortable, to think that their efforts might be considered futile.

It would also have increased my mother's vulnerability. As she lay in bed for 23 hours a day in our living room I knew she was already self-conscious about the enormous strain put on us. Numerous times she took decisions about routine and food that she presumed would alleviate any difficulties in our family life. The sanctioning of that inclination, the condoning of any despair, might well tip the balance in favour of a fatal outcome ahead of further positive experiences. As I tried enormously hard to remove all suggestion that her presence was an unwelcome burden, there could have been an altogether more powerful tacit force undermining me.

Although it has made for uncomfortable reading, I have considered the arguments in favour of this Bill. Lord Carey and Desmond Tutu have given their reasons why it is 'compassionate' to provide an exit door to the terminally ill ahead of their natural demise. The Care Minister, Norman Lamb, thinks people should be able 'to make their own decision about their life'.

These ways of thinking contradict established medical ethics and fly in the face of all logic. The life of a physically sick person is worth as much as a physically healthy person. Importantly, the person in question gains happiness from experiencing that truth. Now that the dust has settled, I see we 'got through' terminal illness, each in our own way. That is why I oppose this Bill.