No I don't think you are the only one going through this!
We have just been through similar with a parent with vascular dementia, the Alzheimer's society has a much more active forum with a whole section on end of life and I found it greatly comforting to "speak" to others in a similar situation.
Whilstdealing with the grief of losing one parent, we are now faced with aggressively advancing Parkinson's in another.
Parkinsons nurses to be honest have offered extremely limited resource thus far, it seems quite frankly that due to whatever type of Parkinson's our relative has there is little to be done. I too seek info on what to expect and it seems there isn't enough honest information out there. Yes it's awful to hear about it but how can you help, understand and help care And prepare yourself when with each new development you're trying to work out if it's all related, a one off or something else.
Maybe the medical know how just isn't there yet, but to hear more practical experience as a carer / relative would be helpful.
Your post really struck a chord with me, sorry if talking frankly is difficult for some.