If you feel that you are truly in danger then hire a lawyer and ask to speak with the district attorney. They can either make sure this guy never comes near you or can help you relocate. You may also be surprised if this guy has a rap sheet he will be on probation or gang related watch list. A lot of the times they seem harder then they appear and have never even had a ticket less alone jail time. Also a mentioned you can still legally own a rifle or shot gun just can't a pistol till 21.
Id have one in every room of the house and make sure the wife knows how to use them also. A cheap way to have watch outside of your house or near your Bike is to invest in a cheap trail cam.