I just want to die

[Remorsal]

As everyone here on the thread stated you're old enough to leave the house already, as for her hitting the dog it's simply just to teach him what's right and what's wrong, if she's doing it for the purpose of amusement or just to get out her stress, that's when you tell her something.

As for your relationship with your mother, try to talk to her about it. If she refuses to cooperate then just leave, try to find a friend to live with for a bit until you find a job that can pay off a small apartment.

I wish you well bud, good luck.