The Decision

Over the last 2-3 weeks, due to illness or other reasons, the number of no-call/no-show or other missed shifts from the home sitter service has increased. There have been a couple of new caregivers sent who, while nice, simply do not have the training, experience, or physical strength and mass to perform or assist with the required care for two elderly adults, one of whom is essentially bed-bound, and one a high fall risk + impulsivity + frequent altered mental status. This puts even more of the weight on myself, with even less rest. 
One night, it just clicked. "I'm done. I can do no more; this cannot continue."
I was glad that it "clicked", as opposed to my snapping. 
But, while it won't be immediate, or peaceful, or without guilt and regret, it must happen.
After a bit over 4 years, my parents simply cannot remain at home; the quantity and quality of caregivers to provide 24-hour care, with at least two sturdy, well-seasoned people during the day and at least one at night, just does not seem to exist. Well, perhaps it does, but it would require becoming the HR department myself, finding and vetting the caregivers, and having to pay 2-3 times as much to have a chance of enticing and retaining them. 
In order to protect my parents, myself, and their decades-long accumulation of assets, for this very purpose of caring for them, this is the last option.