i take care of my dad but.....

so i take care of my dad full time. i work 6-7 days a week as a server. my dad is 50 disabled, severely depressed, heart disease, ephasema, heart attacks, dizzy spells, and an alcoholic to boot. im 26 years old and 1 of 7 siblings and the only one to take this responsibility on. to start i walked through the door tonight and my father was already drunk... he immediately goes to blaming me because his "friends" are mad at me because i demand a little respect. i come home from work to a house full of people more days than not and scare them all off...but thats not the point... so my dad goes to yellin at me and blamin me for everything that has happened while i was at work.. his "friends" kicked in the door while i was away... wanting to beat him up.. his girlfriend wont talk to him because he is a flippin lunatic... he gets in my face and pushes me against a wall.. i push back.. he goes over the coffee table... chases me around the house and i flee out the door... im not a fighter yopu see... ill talk my way out of a fight first. i guess mainly i just want to vent but also to let you all know. i also have medical power of atterny.. which means when he is not in his right mind i can say what to do with him.. to me he isnt in his right mind. but how do i prove this? how do i make this madness stop? how do i get my sanity back?