Hey Frank I just wanna touch base with you and compare my experience to yours.
I was saddened to read of your parents' health issues. There is no way I can say "it will be alright" because it won't be. You will hurt when the eventual things happen. All I can do is offer my experiences and to let you know that this is something that isn't spoken about much, but happens in every family.
I lost my first parent, my Dad, when I was still relatively young at 24 and it was a sudden overnight death. He died in his sleep. It certainly wasn't suspected as he'd just retired months before. In hindsight, I realise I handled his death badly, went right off the rails for quite a few months there & it did change my outlook on life which ultimately made me wanna change jobs and be more real in my expectations. Luckily Dad & I had had a weekend away in the bush together a few weeks before his death and we were developing a more adult relationship together. So I took solace in that he was knowing me more as an adult at the time he died. But the suddenness of it was brutal in impact, both on me, my Mum & all the family.
My Mother died many years later and suffered the indignity of dying with dementia. We were all prepared for the eventuality this time around, but it was both frustrating that Mum fought it for nearly 12 years & embarrassing to you (who would wish their mother dead?). The indignities were frightening, the loss of sanity a real shock to everyone.
I really don't know who got the 'better deal'.... Mum had a longer life and certainly after her own heart scare in 1988 she shaped up and enjoyed life well into her 70th year but Dad did not suffer 12 years of confusion, fright and complete insanity & inability to communicate.
A thing I did realise after Mum left us is that our family has disintegrated. Mum & Dad were our focus. Without them we've all gone our separate ways. I also realise that no one in school, no one in family, really teaches you about these final years of your parents' lives or indeed your own mortality and how it creeps up on you later in life. You have to wing it a lot of the time. I tended to rely upon 'what my parents would've done' or what they wanted. I know that in making the decision to discontinue treatment for Mum when she had reached the final stages of dementia, we chose as one to let her go as we knew she never wanted to be like that.