I've researched with no clear answers. Info about POAs address 'family members' and discuss parent-child or MIL, FIL issues. We went thru a rough patch a few yrs back. My wife gave her alcoholic son a DPOA and of course he abused it and stole over $62K of her retirement funds. We fixed all that and He's now dead. I am now the full-time caregiver for her, but she won't even discuss a POA being afraid to get hurt again. Over the years, we both have built up finances to cover future care so paying for care is not an issue. I realize I'm in a pickle for her future care, but JUST WHAT ARE MY RIGHTS as her husband concerning decisions for her future care? I AM her agent on her Healthcare Directive.
And you tell us that she is now afraid to give ANYONE a POA.
The sad truth is that it is too late for your wife to confer POA upon you if she is not legally competent to do so.
As you don't have POA, and it seems your wife is unable to confer it (meaning she is suffering from dementia) you currently have no way to obtain a POA. I would see an elder law attorney to discuss guardianship. Take with you any and all documents that have been conferred upon you regarding your wife's competency to act on her own behalf, or lack of same.
I wish you the best.