Three years ago, my husband died of brain cancer. It had been diagnosed at the end of September 2011, and he died 22nd January 2012, after three weeks of not being able to get out of bed. He was at home and cared for by hospice at home. He had filled in an advance directive, and we all knew that he wanted to know everything. Whether he remembered it all or not, we do not know, but he was fully involved. In fact, he decided that he wanted no more to eat or drink three days before he died.
There was a GP and a MacMillan nurse, both of whom knew his wishes, as did all the family, because he had made sure we all knew.
It's a shame, Falconbird, that you and your family did not discuss what was going to happen, as now you might be able to talk to your sons about it.
I still have times when I wonder if we did the right thing, by allowing him to stop eating and drinking. But it is what he wanted.
My husband also had cerebellar ataxia. He had a neurosurgeon looking after him for two years after we moved to Durham, and we wrote to her, and discussed with her what had happened, and whether they had missed the brain tumour earlier when they were taking brain scans because of the ataxia. After he died, they checked all the scans very thoroughly, and they showed us them. We are certain that whatever was done was done to help him. Are you sure it's not possible to talk to anyone medical about him?
This is the sort of thing that should be put in an advance directive and given to your GPs just to make sure that those left behind are not unduly upset by what happens.