Family conflict, please could someone offer advice or help?

I'm having family problems, and I was just wondering if anyone could help. It's my mother. She's starting arguments in our family, and I'm scared she's gonna split us all up. It usually starts with something stupid, like a disagreement with one of her friends. Recently, one of her guy friends has been pressuring her for a relationship, which she just does not want. He won't accept this. He argues with her. Whenever she comes home from nights out at clubs with him and her other friends, she takes it all out on us. She places the blame on my sister and her boyfriend and me for the way her life isn't working out. she picks on my big sis for things like not doing the dishes, or being a day or two late for the rent, which she does always pay in the end. She threatens to kick out my sisters boyfriend for being out of work, due to a recent run-in with the law, even though he's looking for a job. She shouts at me simply for not looking happy, or not weighing up to her high standards of me going to university in the future, or taking up a course for some sort of work experience. I don't believe she is a good mother. We try to tell her where she's going wrong, but she talks over us, and doesn't listen. She then threatens to purposely try to be a bad mother, as she refuses to believe she is doing anything unfair, and thinks we are ganging up on her because we hate her. Which I have to admit, is becoming true. My sister is threatening to move out with her boyfriend, which I don't want, as I need a big sister around and her boyfriend has become almost like a brother to me. (He himself has had a bad life, last Christmas he was living on the streets and was put into hospital for bad pneumonia.) This is driving me crazy. Mum's always put things before family. In the past she has had many different boyfriends, (I've lost count) and has placed them higher on her list of importance than us. I know I shouldn't talk bad about the woman who brought me into this world, but I wish she hadn't. I've been miserable all my life, and now I have this to add to it. I'm pissed as to why no one can get through to her. She bad mouthes us to everyone she knows. Counseling does not work. (For me or her.) Something has gone in this woman's head.

Maybe I shouldn't be telling you this, but I figured people of my age who know what bad life is like would have better chance of helping me than a snooty psychiatrist who thinks they know everything about life.

I don't mean to burden you with my problems, but I would appreciate it if anyone could help in any way they can. Please, any advice?