My mom is 79 with dementia. They are both still in their home. I do the grocery shopping, make most of the meals, do the wash, take them to dr appts, sort their pills, lawn care, etc...I hired someone to clean and got a visiting nurse to check on them. After 2 months, he told all of them not to come to the house anymore. It took me a long time to get the nurses to come, because my parents refused their help at first. Now my dad has started yelling at me that I am a phony and why do I work so much...or...why do I keep trying to get all his money (he has no money)? He has no dementia, but I did hear the possiblity that the prednisone he is taking might be making him agitated. He takes his anger out on me, and it is usually sudden. Today, I picked up their prescriptions and dropped them off. While I sat at the table setting up my mother's pills...he came over and started yelling at me that I was no good and didn't care about them...and then said my husband was a jerk...this happened a few times before. Could it be the prednisone? I have one sibling that lives out of state, so I am all they have. I have actively been taking care of them for over 2 years now. The next time I go over, he will be fine for a few minutes and then he flips out. I am so frustrated. I am coming home in tears most of the time, but I have to go back and take care of them. The doctor's office tells me to call the police. On my parents? I can't do that.
Best of luck in getting mom into a good facility and in finding out something about what is going on with dad.
Your dad is having his own stress with your mom's dementia and he no longer feels in control of his/their lives. This also can contribute to his lashing out.
He has rejected help for the same reason no doubt. He is facing his own mortality and loss of control. That is devastating to anyone.
Have you ever been able to talk to him honestly and intelligently? If you haven't before don't try now. He must trust/respect someone and that is the person you need to get to have a talk with him.
The steroids you can't do much about.
There is also a temporary or "situational" dementia that he may be experiencing. The stress of this "situation" may have brought that on.
Please explore all avenues and options...that may include a reality that none of you would prefer. You must preserve yourself and your wellbeing as well as their's.