Help dealing with an alcoholic father with a raging case of depression. Any advice?

My stepmom passed four years ago. He has literally given up on life. He is passively killing himself. He drinks and smokes. He has fallen five times outdoors (we live in the north) and has laid out there for hours before being found. One such fall resulted in a broken hip. He has had multiple TIAs, so many times he doesn't remember how or why he fell or how long he laid there before being found. He absolutely refuses to take prescribed meds. Only sees a doctor when he is hospitalized. He absolutely does not care one bit how his situation affects anyone and everyone around him. He refuses to consider assisted living. He expects us to drop whatever we are doing when he needs something, which is almost daily. We do have in-home caregivers that come daily as well as an in-home nurse who comes at least once a week. This past year alone, I have used two weeks of vacation time due to his hospital stays and doctor appointments. I also have a sick mother who has two heart attacks this past year. I have used nearly as much vacation time for her as well. I am tired. I dread calling either one of my parents for fear that I will need to take one of them to the hospital. The nurses in the ER know my husband and I by sight. I am practically on a first name basis with the 911 dispatchers. Between both my folks, I have called 911 six times this year. I am beyond frustrated and I have major guilt for feeling this way. Any advice?