From the sound of it the court isn't even going to hear your mother out on this. If your father's attorney is at all wise he'll get a doctor's note saying this woman is unfit to raise children and you'll have the option of going into foster care or living with him.
I mean, there's not much to bed said on the subject. stuff sucks and it will continue to suck. I suppose if you have a god or higher power you believe in, pray to it that your mother doesn't murder a bunch of people. Aside from that there's not much to do.
You said you have siblings, I'm assuming they're younger than you. Comfort them, remind them that you're there and you'd take care of them in lieu of your mother. Tell them that things will be OK. Lie to them.