My father is 98 and still driving. His wife is 90 and they have been married 25 years. She has dementia but her kids are ignoring it as my dad is her baby sitter. She yells at him and is constantly telling him his five kids are evil and have stolen over $100,000 of her clothes and costume jewelry. She insists that we have bugged the house and she has barricaded the doors with furniture, etc. My father loves her and is putting up with her outbursts, but it is wearing on him. He calls my brother crying about once a week. Any suggestions are welcome as we feel she is abusing my father, but we are not allowed in the house and she hangs up the phone if we call.
Him calling your brother once a week crying about this makes me wonder if he has the beginnings of dementia. My father did this to me when he was in early dementia as my mother was very hard on him, but she did not have dementia, it was her Borderline Personality Disorder and she didn't understand his limitations.
Sounds like they need some outside help. You could call the Agency for Aging in their area and find out what resources are available. A call to Adult protection Services telling them about the situation may or may not be helpful.
If you know who your dad's doctor is you could contact him (email or letter) describing your concerns and asking for direction.
I flew across the continent and visited for a few days with my parents to find out what was going on and was able to advise my mother that my father likely had the beginnings of dementia and was not able to cope. She managed better after that. However this is not quite a parallel to your circumstances.
This is very difficult for all of you. It would be better if her kids would get involved and get her evaluated and treated. Otherwise I think you have to work through your father. I am so very sorry you all are going through this. I know it is very challenging and your heart is breaking for your dad.
Sorry.
Tell Dad that you cannot help. Tell Dad that he is far too old to take on this kind of care for someone so severely demented.
It would be my guess this has been done?
If Dad is competent to make his own decisions then he has made them.
This, of course, is time-stamped to end at some point soon in any case, isn't it? Because "something will happen" and you will get "the call".
At that point you can insist on some intervention in this in so far as it can be done by hospitals, rehabs, and etc.
As to the title question, of course this woman has dementia. It is quite beside the point what she threatens now. She hasn't the physical or mental acuity to carry forth any threats.