Hi hun,
sorry you're going through this. I strongly suggest you go to AlAnon and read here as much as you can. Also maybe you'd like to check the subforum Adult Children of Alcoholics (ACOA) on SR.
My dad was also an A, he passed away 11 years ago at the age of 53 due to alcohol related illness. I guess living with him I pretty much felt the same way you're feeling now. I never spoke about it to anyone. I don't know if I felt deep down it was somehow my fault, but I know I felt it was my job to make it right and put up with it. I guess like you I mistook our roles, I was considering myself to be a parent and not the other way around. I minimized what he was doing and I rationalized it with it's not too bad and he can't do any better. Today too I know he couldn't do any better but today that knowing comes from the different place, the place I've reached after working on myself and all my emotions, and not by surpressing them and not knowing how to deal with them as it was when I was your age.
I think it is crucial for you that you educate yourself on the disease of alcoholism. Not only for this point in time of your life, but for your future too. Because hon, you're bacoming the person you're be until the rest of your life, and living under these circumstances can prove dangerous for you in the long run. You're larning to live your life in the way that you taking care of someone who seems unable to care for himself. You're creating a pattern of a bahaviour that you'll take as normal in your life to come. Thus it is likely in life you'll be searching for partners that will give you this same kind of life, the only one you know how to live.
You're really young, and I don't know if any of this makes sense to you. So I will not talk more about it, I just hope you'll start working on yourself and educate yourself about this disease and the way it affects people how are living with it.
Your dad had a relapse, maybe he'll seek help and continue working on his recovery or he'll continue drinking. No one can know that. This is not about his love for you, his drinking doesn't mean he doesn't love you enough, but maybe he doesn't love himself enough, maybe he's not strong enough, whatever the reason it is not your job to save him, bacause you can't save him, no one can but himself. That's the nature of this disease.
And aslo a big issue: Shame. There is nothing you need to feel shamed about. Don't feel ashamed for what your dad is doing. His doings don't say anything about you, it is not your job to hide it, as by doing that you're only making things harder for yourself.
Again, I'm so sorry you're going through this.
You seem like a really smart young girl, and even though I don't know you I feel proud of you.
I'd really like to help as much as I can. You can PM me if you like.
HUGS