My dad is an unapologetic alcoholic. There's nothing I can do about it. He's an adult. Adults have a right to drink themselves to death if they choose to.
I have a right not to interact with someone who is making that choice.
It is very upsetting and stressful to watch a parent making a self-destructive choice, and our natural instinct is that we want to interfere and save that person. But you can't save people from themselves, however much you love them.
What kind of support do you have, if your family isn't supportive of you? Have you tried any type of therapy or maybe an Alanon meeting? Those things have helped me a lot. The best thing to do is take care of yourself. If that means limiting contact with family, then those are the consequences they get for mistreating you, however much they try to make you feel guilty.