Your dad seems to have put you between a rock and a hard place. That's got to be disconcerting for you. At least you have been able to get a little perspective on your own about his possible condition. That's really smart of you. There are sources on this site that can give you some guidelines as to ways you might approach your dad so he can see he has a problem and can get help. If he cannot acknowledge he has a problem then there is nothing you can do. Don't feel guilty. It's nothing you did wrong.
I sometimes think that the moment a person becomes a parent some form of emotional DNA takes over to make them capable of creating guilt in their child. You don't have to be a Jewish Mother.
I know how badly I felt when I had to go against may father's wishes but sometimes you just have to. Now I know more about my father and I know that I needed to get distance from him. it's like you said, though, you won't even be that far away!
Do what you need to do. Love them and let them know you love them but gently do what you need to do.