Do you expect him to get physical? If you don't live together, meet him in a public place like a coffee shop
i'm sorry you are going through that. you should move far away for a little while and tell him over the phone. Don't tell him where you are going and make sure that everyone you know does not tell him where you are at either. break up over the phone and Never look back. you can do this. you deserve so much better, and you will find it. Good luck!
say it straight up and get order of protection
This begs many questions. Has it gotten physical before, as in coercive? And by not being with, do you mean breaking up/leaving? It sounds like you may be captive.
The first, best step is getting allies. They can protect and offer perspective.
Leave and don't come back.
Call it off in a public place.
Just unfriend him on Facebook.
That'll do it!