I Have A Sociopathic Ex-boyfriend Who Is Harassing Me, Threatening To Ruin My Career, And I Recently Got A Phone Call Saying That He Was In Town And Had A Gun. The Police, My Family And A Few Friends Know. How Can I Ever Feel Safe?

I would first stay somewhere else for a while, someone that he doesn't know. Tell your boss what is going on and change your phone number.  Carry a can of mace and some kind of a club. Depending on your job, they can usually tell security, if they have it there.  Record all of your phone calls if at all possible for proof.  I think you can get a restraining order, if you tell them that you fear for your life. Play hardball with him. Don't show him you have any fear.

I was in the EXACT same situation.  First, if you can afford it, get a lawyer.  Get them to write a letter and have it hand delivered saying if they contact you again, you will file an antiharassment order.  If he shows up to your house, you immediately call the police.  Even if they don't do anything, ask them to file a report and state that you are fearful of this person.  Tell them he is controlling, harassing and stalking you and owns a gun. Never let this guy know you are scared.  Some of these guys are scared of male authority, some are scared of the cops, some are scared of judges (even though they will say otherwise).  Find out their weakness and protect yourself.  Document document document.