Dad a functional alcoholic???

I am 17, a senior in high school with a younger sibling, my dad is an emotionally abusive alcoholic. An alcoholic so much so that he drives 1 1/2 hours to go to his favorite bar where he drinks all day long, and when he is ready my mom and I go to the bar to pick him up....we park and I go into the bar where I wait until he is ready and I find someone to help me carry him out to the car. After we leave, one of us rides with him and other one drives the other vehicle we drove and we start home....it always ends with him angry, us frustrated or sad, him belittling or pestering us to our last end, or sometimes he is really mushy and just wants to snuggle with everyone......I've dealt with this since I was 3.....how do I keep it from bugging me and how do I deal with it for my sibling when I go to college next year??? No wise cracks please....it isn't funny.