Sending sympathy to you and those in this situation.
We've been there with my late MIL;we had to watch her decline and become an empty shell first physically then mentally with a degenerative condition that attacked her nerves.
So many times we were told she wouldn't be here much longer,so many hospital admissions,the middle of the night you need to come to the hospital calls,the having to make the decision to put an DNR in place.
She couldn't do a single thing for herself at the end,she was incontinent with a catheter and an adult nappy,she couldn't swallow and had to be peg feed everything;food,fluids,meds,she lost her fine motor skills,couldn't read,use her phone or hold a toothbrush.
She lost all movement from the chest downwards,lost the ability to talk properly and her mind went too.
She lost a ridiculous amount of weight,lost pretty much all muscle tone and had her skin was awful.
It was utterly cruel keeping her alive,my MIL before this happened and was healthy would have been horrified at what she ended up becoming.
Trying to get help from social services was a terrible battle;we nearly got her into a care home once but an assessor from the NHS put the brakes on that despite how disabled she was.She eventually went into a care home a month before she died.It was too little too late.
She passed just days before Christmas 2016.I'm not going to lie,it was a relief,we didn't grieve the traditional way per se;we'd already made our peace with losing her and had had said goodbye so many times before it actually happened.
We still miss her and it's hit home recently as my first grandchild arrived a few weeks ago;she would have been delighted.