JamieLee: You must remember to take care of yourself; otherwise you won't be able to help your Dad or your brother. Any kind of a day-care service Shaybo mentioned is worth looking into.
My friend's Dad has quickly deteriorated with Alzheimers. She and her family did everything they could including buying a new home so he could live with them and there weren't stairs and such that were difficult for him. But it ended up that he needed hospitalization and will have to go into a care facility.
I can't imagine how difficult it is, but know that you are doing the best you can. You are a very good daughter. And in your Dad's heart, he know that!