Hello Tash, I'm sorry to hear what's going on for you.
Soberhawk is right, alcoholics usually just end up drinking anyway no matter what. You can try to understand them, but it's hard and impossible, as often people do just keep drinking and it doesn't make sense.
You do need to look after yourself at the moment, could you start seeing a therapist while getting support from your relatives? There are also Adult children of alcoholic meetings and al anon, it depends how you feel about going to groups.
It can and it does get better. I'm putting boundaries in place around my interactions with various family members and others now (I'm trying to learn detachment). It takes some practice, but you need to do what's best for you.
Focusing on yourself and getting care is important for you, you can figure out other things as you can along. Let us know how it goes.