If you had a falling out with your roomate, best bet is to go your own way instead of attacking him.
Responding to the "Additional Information" you provided, rather than your original question: you sound as though you may be eligible for a Peace Order, popularly referred to as a restraining order. If this person has harassed, threatened, or assaulted you within the last thirty days, you can go to the District Court or a Commissioner and file a petition for a Peace Order.
Such an Order can be written to prevent your former roommate from having contact, going near your home, work, etc. Violating a Peace Order by continuing to threaten, harass, or abuse is a criminal offense which can result in being jailed.
This is NOT legal advice, is GENERAL INFORMATION ONLY, and does NOT establish an Attorney/Client Relationship. Therefore my answer cannot address your specific legal situation and you should not rely upon my answer in your legal matter. I am an attorney licensed in Maryland