What you are feeling is typical. You have a right to be angry, confused and exhausted, both mentally and physically. This is a painful process. Give him support, love and be grateful for every second you have with your dad. He knows it's hard on you also. Many times it is harder on the caregiver than the patient. They have an inner strength that is inspiring. Take care of yourself; eat, sleep when possible, feel no guilt. God bless you.
Diane