David,
You didn't bargain for this and really shoudn't even have to be in the middle...
Definitely talk with the police where you live,
ask them to maybe communicate with the police where that guy lives.
I'd also suggest you get the "down the street family" involved in talking to the police in your town.
Maybe talk with the City attorney, or the prosecutor, or DA...
Consider explaining to, and talking with a private practice attorney....while it shouldn't be your problem, it has become too much of a concern for you.
And use that attorney to help you talk with the local LE folks and DA folks.
You don't have to live with this kind of concern But it may cost you $'s to make sure that is a fact rather than a theory.
It sure wouldn't hurt to be able to protect yourself and your GF just in case that jerk comes calling.....My wife won't have anything to do with weapons either.....thats why I only keep a few, loaded, out of sight and close at hand in our home ( no minor children here anymore).
Personal opinion is this just isn't right!....but you may have to spend a few bucks with an attorney to get to a place where it isn't a risk either.
By the way you wondered how that guy got your number...
Most, if not all, real estate offices have a criss cross book...where you can search on a phone number, an address, or a name...and get the others.
Also, the county offices have records of who owns what real estate.
I'm not being creepy....but you are 28...you lived in 2 different locations in MA before you moved to your current location in NH? IF that is accurate, it took me less that a minute to find that on the internet...at no cost.....
If I wanted alot more detail, it would cost, but I could get it.....and I am easier to find out about on the internet, probably, than you are....
So use the legal sysem to help out....you don't deserve the crud you have, let alone might, have to endure.....
And....just for the heck of it, arm yourself, use deadbolt locks, and don't worry, be prepared.