I have POA of my Dad, who has dementia, what can I legally do with this authority?

My father has dementia. He refuses to take care of himself physically, will only eat junk food such as ice cream, candy, donuts, pop and then relying on a nutrient drink. When I have made meals for him he eats 2 bites and then it sits in the fridge and rots. I have bought food for him to prepare and I have to throw it out because he refuses to eat it. He bathes maybe once a week, his toe nails are inches long. He has more or less destroyed his home and refuses to let me make any repairs. His memory is getting worse to the point that he can't remember my sister's name, things he has done or forgot to do. He refuses to follow doctor's orders such as exercising and eating properly especially after triple bypass surgery. His doctor will only assist if I file for guardianship otherwise he will not act on possibly placing him in a nursing home for his best health alternative and safety. He refuses to follow simple requests I even ask of him to do. I don't know what to do. I can't sit by and watch him destroy himself and everything around him. I don't know if the POA allows me to place him in a safer enviroment or what. I do not have the funds to pay for guardianship. I had him live with us for a while and he would get up all through the night and smoke and leave his cigarettes lit in the ash tray. So this ment if he got up I had to get up as well. He burnt holes in my furniture and carpet. He wouldn't use soap even when I forced him to bathe that his odor was so bad that it filled our small home. He refused to eat more that a few bites of the food I prepared even I prepared food he liked. But if I had junk food he would eat it. It got to the point that he was effecting my mental health and marriage. The doctor told me to send him home. The doctor advised me to step back and let him do what he wants. Well this isn't working, it is getting worse. My life is at a stand still when it comes to his care. He calls me all hours of the day to do this or that. Thinks he is capable of doing. My husband and I couldn't even go away to celebrate our 25th anniversary because of the fear he would burn down his house. I have had a nurse check in on him a few days a week. When I told him of his eating habits they told me not to take him out to eat but rather make him make his own food. I did this and he still wouldn't and the nurse did nothing about it even when I expressed my concerns. I had the State come in and they blew me off. I am at wits end on what I can do. I am trying to return back to work and I can't spend all hours of the day and night watching him or being there when he calls. My family needs me to return back to work financially. I have hired a woman to clean his home but he only allows her to clean certain areas of the house. If he hears a clink or a noise he comes in and treats her as if she is stealing something. Now he is relying on her to transport him for his personal needs even when I have instructed him that he is my responsibility not the housekeepers. As far as a know he isn't paying her for these additional services. He wants he car back to drive himself to church but I had his license pulled because he did 2 hit and runs while driving with me in the car. Then I found out that he had cartaracts and he had lost most of his vision rather than telling me he couldn't see. I am afraid someone is going to report me to the State for neglect. I am so scared for him and myself. Any help would be greatly appreciated. Thank you.