Sorry if I'm butting in here, but I'd like to give my two cents, as well.
It sounds like your mom might be depressed or suffering from some personal or emotional issues; in either case, it's not okay for her to lash out at you or your sibling.
I think it would be a good idea if you talked to a councilor, or a good friend - someone you trust so you can get your feelings out.
Personally, if I was in your situation, I would try to save up money for my own apartment. But, if you can't just yet, I recommend that you either find a good, safe friend to stay with (follow their rules and pitch in with the house work) until you can earn the money to move out.
Your mom should go into therapy, too, but you can really only offer it to her; she has to want to go and she has to put in the effort to go and get help for herself.
If your mom is hitting you or your sibling, you need to call the police. There's no excuse for that.