PTSD (and all that goes with it)
Caretaker for an autistic son
Caretaker (or increasingly a caretaker) for an aging parent
All your other roles

Even if you were not struggling with depression and PTSD, filling the duties of caretaker for two individuals at different stages of life with unique challenges would be exceptionally taxing. How much more so for you.

The only "respite care" you've received recently was a hospital stay.

Questions: You've been wrestling with the Question for a while. Is a natural will-to-live still active in you? Are only the four "pros" keeping you here? Is something continuing to energize you beneath the conscious level?