You should, I'm sure your father would want you to. I don't know if you have your own family or plan to but, it would only be fair to them, and youself.
If you are having a hard time dealing with it and you are a religious man...talk to your priest or rabbi or etc... for guidance, strength, and a healthy vent. You already know going to the bottle won't work but, going to your family might. Just being there sometimes helps...
I've seen alot of suffering and death in my life time, and the one thing I learned from it is... you make the best of what you have at the time. He's here and now... not then and gone... Damn it if you want to do something special for him...just do it (provided he's up to it), tell him it would make you feel better. You know what it will, you'll look back and think to yourself,'I'm glad I could do it for him, and he was happy.'
This is the time you should spend with him, and not worry about the worst. Think about the happy and what makes him your dad. Whatever is going to happen will... whatever you make of that time will last with you forever. I know you will be strong for your family, and that you aren't as weak or confused as you think you might be. You prob. already know what to do... jsut do it man. My blessings to you, your father, and your family.