I'm not sure if you read my previous post on your other thread, but a paramedic has no authority to suggest a blood sample should not be taken.
I'm not sure why they would - potentially they felt sympathetic to your circumstances and wanted to be a good samaritan, but unfortunately they have mislead you. They can't give evidence on your behalf, as in order to request a sample the doctor in charge of your care would have needed to say you were fit to give a sample. The medical opinion of a doctor will trump that of a paramedic. If they tried to give evidence for you they would also likely lose their job, and may already have been reprimanded.
The issue of suicidal people drink/drug driving is not new. I have seen it many times. It's unfortunate, but because drink driving/drug driving/failing to provide is a 'strict liability' offence your state of mind or intent is not considered.
It's also worth considering that while harsh, it is fair. A drink/drug driver is just as dangerous while suffering a mental health episode (if not more so) and it is in the public interest to prevent you from driving. Ideally, there would be a means of banning you without giving you a criminal record, but if that were implemented every drink/drug driver would suddenly claim to be suicidal as a means of escaping punishment.
So while I'm not here to judge you, I want you to understand it's not unreasonable to seek prosecution in your case. I would encourage you not to consider this a huge setback to your life, and to talk to someone about the issues that lead you to the accident. Plenty of people in this forum will share the same circumstances as you.