In a possessive/abusive realtionship, I need out!

I have been in a relationship for 5 years actually 3 days ago was our anniversary.not that either of us remembered. I am afraid I have let it go way to far. I live on a 28acre ranch about 7 miles either way to town. I live in a nice newer trailer on this property, my elderly grandmother(75) lives in a 3bdrm house about 20yrds from my trailer. I made the mistake of letting my long term relationship move in with me. I am currently clean and sober, and almost off of probation. He is not and is on the run.
So all of his stuff is at my house, I cannot leave my domain for any extended period of time because I must be able to take care of my grandmother(who has diabetes, heart disease, and a bad case of gout crystalizing in her knee), I cannot have law enforcemen come by and supervise because I know he has all kinds of paraphanalia everywhere, and after the couple of years of drug abuse, and the almost 3 years of isolating from my drug addict friends, I litterally have no where t run anymore. (tears well in my eyes as I type) I seriously need him gone but he wont go. When we get into arguements it turns physical all too quickly now and with such tight quarters, he blocks me in so that I can't leave. Litterally cornered curled in a ball asking him to please just let me go outside, he repeatedly tells me to shut up. He puts his hand over my mouth cause I usually cant stop whimpering, and with a nose full of snot I usually have a hard time breathing.
I sometimes leave him in town, but it never fails that one of his stupid friends that I have asked not to give him a ride to my home, gives him a ride to my home.
My nerves are shot my self-esteem is slim to none on a good day, and I dont have any kind of support system left.

I really really need help, Today he came back (one of those great friends of his dropped him off) and started accusing me of all kinds of things, he is insecure, and I have never given him any reason to think that I am cheating, but thats what he goes into. So while he is rambling I managed to grab my netbook, phone, wallet, and keys, and jumpped in the car and drove down the street.

I have no where to go, its time to feed the cat, and I am scared to go home. This is not fair. I am a decent human being, I always do my best to help anyone who looks like they need it or anyone who asks for it. So why am I stuck with no help, no where to go, and no one to talk to but an online forum?

Someone please help me! I cant do it anymore and I cant just give up, and run away because my grandmother needs me.

Sincerely,
shot nerves, brused body, and squished ego