I can totally relate to your feelings of guilt and the struggles of informing someone of their memory assessment. My mum has been in denial all along . It's different for everyone, though- she's now 100, was showing signs of memory loss and confusion 3 years ago and I had then asked the GP to write to tell mum she was due for a general check-up. They wrote that she hadn't been seen at the surgery for ages- the GP went along with this but she refused the full assessment.
A support worker from Alzheimers Society came to my rescue 7 months ago. ( I'd phoned the helpline in my area ). I was encouraged to keep writing updates for the Memorory Assesssment Service. The MAS don't reply to emails but I wanted it all to be on record. You can phone them too. Everything I wrote was taken note of for the actual Assessment. I also shared my concerns with mum's GP as POA. Before the big day, I explained to her it was a well-being assessment, about her memory, in case anything ever happened to me we would have a future plan in place for her .Things can get to be more tiring / complicated, as we get older and to feel secure in the knowledge that there was a GP record if, god forbid, she or I become hospitalized or ill in the future. I tried to play it down. She said she didn't want to think about the future., but agreed to a phone call from the MAS and politely accepted their offer.
I said the assessment was to make sure people had the best possible quality of life and remain independent for as long as possible. This went down ok, but may not do for everyone. I also said that the GP had asked for this assessment( true) and it was to find out the cause of the memory loss ( true) . Good luck with your journey!