So sorry to hear this mate, and totally agree.
We lost mum in September after a 5 year cycle of dementia. I watched weekly the physical and mental deterioration of a person I obviously loved dearly. We went the different direction from you where we kept her at home with dad, but had every type of specialist carer in the bungalow making sure she was made as comfortable as can be. Being only last week, it's still incredibly raw with yourself and the family, and I hope you're getting through it as well as you can.
I never want to go through what I watched my own mum go through. I would personally want the Dignitas model and feel very strongly that it should be implemented. I already have one friend who chatted to me about his own dad in the final stages of cancer getting on that plane to Switzerland and coming back as ashes.