WTF is wrong with me?

Today is an extremely shitty day. I don't know what the fuck is wrong with me. People always tell me what wonderful, polite, kind and thoughtful children I have raised, but you wouldn't think that if you were around them today. I don't know what I did wrong or what I did to ever deserve to have 3 children who act the way they do towards each other. They are nasty, hateful and just plain MEAN to each other. I'm sick and tired of it, and I don't know how to stop it, because they refuse to listen to me, tell me that they hate me, and just generally do everything that they've been told not to do. I give up, I'm tired of listening to it, and I just want it to stop. I'm sitting here locked in my bedroom right now, because if I go out into the living room where all the fighting is going on, I'm liable to have a nervous breakdown and that would not be good. I truly can not wait for them to be back in school so that I only have to deal with it for a few hours a day. My 17 year old treats me like shit and prefers the company of a highly dysfunctional family down the street. My soon to be 15 year old mopes around and only wants to play video games all day. The 11 year old has learned from the other two just how to aggravate the other two to the point where I just want to explode. No form of discipline has worked with these children. I've tried everything under the sun, short of corporal punishment. I don't understand why they can act so differently outside the home and so hateful inside it. I just don't get it, and don't think I ever will.