I think I know so much of how you are feeling. I am 26 sweetie and I am going through the same thing, but my father's problem is alcohol and probably cocaine (he just wont admit the coke although all the signs are there) If you were to see some of my posts you would see that I am asking the same questions you are. I am married and have 3 kids of my own and my husbands. I am finally getting to the point where as hard as it is I am beginning to accept that the choices he makes are his alone, at least most of them. Like you, I want to help as much as I can and our fathers are so lucky to have our support. We are also lucky to have them alive. I hope to be able to help you in whatever way I can PM me if you want to talk more.
Hope I can help
daddysdaughter