Hi Carlos,
Very sorry to hear about this trouble with your father. My family has been having a hard time with my grandmother's Alzheimer's as well. She still insists on being independent, on the other side of the country from us, even though signs are obvious she's struggling. Old world stubbornness.
Just remember that alcohol will not change your dad, will not change your relationship with your dad, or change your emotions. You'll either come right back to the same situation (only with a hangover and guilt) or you wont come back at all.
You can do it! Really, you can. And be careful of those "not sure" statements. Not speaking for you, but I know when I made them what I really was saying was "a part of me is making plans to go drink." In any case, you don't have to be sure, all you have to do is try.