Dear GLP, I'm in need of advice for an extremely complicated situation - My mom and I are living DOOM everyday

Before you ask why I'm asking for advice here, I'll tell you - I'M DESPERATE!! I'll get to the point since I imagine you're upset that I've torn you from the doom gripping the world right now. I've got serious doom happening right now, in my daily life. It's not bad for me though, it's the worst for my mom.
My dad is a meth head, he lives with my mom and torments her daily. Since he's a meth head, he can stay up for days and torture her. He's delusional and so paranoid, he thinks when he goes to the bathroom a guy pops out of the closet and starts fucking my mom, and jumps out the window when he comes back. You may be laughing at that but I'm dead serious, I am not joking at all He thinks there's people in the bushes behind his (my parents) house, when he comes home from work he'll like crawl through the window one day, and bust in through the back door another expecting to find my mom fucking someone or doing meth.
My mom DOES NOT do meth, but my dad is so paranoid he thinks she steals his and does it. When he's home he NEVER takes his eyes off her. When he doesn't have dope, he thinks she gets it some how and is keeping it from him. An example (This is how my mom told it to me) - one day his dope head buddies came over, she was reading magazines (There's like a stack of magazines on my moms coffee table) she said she leaned up from the couch to put one back and grab another and her phone fell out of her lap onto the floor, she picked it up and that's that. After the dope head buddies leave, he swears up and down one of his buddies threw a bag of dope into the floor in front of the coffee table when he wasn't looking and she 'pretended' to drop her phone to pick it up.
It's something like that daily - several times a day. He punches her sometimes, and pushes her down but it doesn't happen all that often (doesn't make it any better) he threatens to kill her daily. I live a few blocks away and I'm constantly driving 90 to nothing to her house 'cause they're arguing.

Here's the complicated part
I live in a rinky dink shit ass town, and the cops don't give a FUCK about anything. The police have been called on SEVERAL occasions and it's OBVIOUS that something has happened, but my mom either won't complain or leaves before the cops arrive and the cops won't do anything.
It's gotten to the point when the police are called, they take a fucking hour to come (The towns population is 600 - how much can be going on to where it takes an hour??)
It's getting worse, and I really really fear for my moms life. She comes to stay with me sometimes but when she does my dad just calls 24/7, bangs on my windows and doors all night.. She won't stay long because she says I shouldn't have to deal with it... She's right, but I can't just ignore it.
I'm so close to losing my job, I've had to drop out of school over this because I'm afraid - I feel like I have to be right there all the time or he's going to kill her...
This is hell, pure hell... I know there's people who have it worse... I just don't know what to do and I'm losing my mind. I don't know what I expect you guys to tell me to do, but - does anyone have any advice... Anything? Advice, suggestions, opinions, and kind words are much appreciated..