Sucks to hear about your situation.

About the law getting involved-

You should probably file an identity theft report with the cops as it pertains to the troublemaker.  After all, if he's gonna go after you for assault-and-battery, then you should return the favor for his defiling your online identity the way he did.  Quid pro quo, I always say.  

And make sure homeboy didn't do anything else while masquerading as you... like ordering up a buttload of monkey porn on Amazon.com or something.