OP, you've said:
All this chemo business is new to us both . It’s scary … but I suppose I expected him to be more on top of things as the one who wasn’t ill and going through all this rubbish.
I think you've answered your own question. I nursed my mum through the last six months of her life: bowel cancer, ileostomy/ stoma and then endless fistulas opening up and leaking. Nasty, smelly, deeply distressing symptoms for her, and me, to deal with. I didn't imagine the last few months of my mum's life would involve me dealing with literally breath-taking faecal discharge and having to change her sheets three times a day with a smile and a 'don't worry, Mum, we'll get this sorted'. All the while terrified (what was going to happen next? how much more horrible could this get? is this symptom or that development normal or is it 999 time?, how long was I going to have to keep going?) while grieving for the lovely mum I was going to lose.
None of us can ever be prepared for any of this. Despite having home-nursed three cancer patients (Mum, a friend and an elderly aunt) so far, I had no idea that you couldn't reheat a quiche for them.
I know you're going through hell, and I wish you the best, but go easy on him. I'm really pleased to hear that he made himself a roast lamb dinner and had a glass of wine because I know how grim it can be to be the carer and how little pleasures can make all the difference. I presume if you were able to eat a roast lamb dinner he'd have served it on a tray for you. He's likely to be in his 70s; you've been married for 50 years and have got into your roles. He's having to learn an awful lot and as you yourself say it's all new and you're both frightened and anxious. How about telling him how scared you are rather than expressing it through anger?
In the case of my mum and another elderly relative neither the MacMillan or Marie Curie services were the slightest help because I and my sister (we took turns looking after mum) were deemed capable — even though we both had full-time jobs. I would have thought that at your ages, and in the circumstances, you might find it easier to get some home support. Could you use Attendance Allowance or similar to buy in some qualified assistance? I know you're having a terrible time, but I assure you he is too. Just a different sort of terrible.
Good luck: I hope in six months' time you'll be able to look back on this as the low-point in your recovery.