trying to help/deal with, my almost 99 YO father... [View all]

I am frustrated and angry. He is in pretty good health, but he is taking care of his Parkinson's and demented wife and it's wearing him out. He's hurt his back lifting her.
I have researched resources, like getting respite care and he gets annoyed and refuses. He'd like me to help, but she is much too large for me to even attempt to lend an arm. I did once and she just about pulled me over. Not to mention, I am not qualified for such a task.
The exhaustion is wearing him out. He fell himself the other day. He fell on his face and needed stitches on his nose and forehead. He drove himself to the hospital, which I don't think was a wise choice to do. He was bleeding and he could have had an accident, fortunately, he didn't.
The other day he asked me to sit with his wife while he shopped for groceries. I drove up to his place, not a long drive, but an 18 mile round trip in hills and winding roads. After waiting around I asked him when he was going shopping, when he then decided he wanted to take his wife, which means getting a woman who can't walk, down a flight of stairs and into a car. I refused to go with him on that trip, which would have been a 3 hour ordeal in addition to my then added trip to my home.
He complained about how tired he is and I told him (again)he didn't have to do it he could get respite care. He then threw some things across the room and told me to get out.....I did. Actually, I was afraid of him because he was very abusive me as a child and he used to beat and he had "that look" in his eyes. He still is abusive verbally and emotionally. He tells the neighbors how proud he is of me and how much he loves me. To me it seems quite different.

I am looking for options, considering Adult Protective Services, which was advised to me by a senior facility.

His wife has children, but only one female, who is sick herself and not able to be a lot of help. The males are not much help at all.
I think he is also in some stage of dementia, and since his fall, it's accelerated. Neighbors think he's a great guy, but, of course, they don't see the side I see. He prides himself for being a "Superman". Advice is welcome.

I am a petite 74 year old female in pretty good health, but in no way capable of dealing with their physical needs.