You've been given good advice to not have any contact with the BF. Follow it.
Also, you've been told to get a restraining order against him. Follow that advice as well. The guy has threatened you. You have documentation of it. More importantly, you need to establish a document trail demonstrating that you did everything in your power to act as a responsible law abiding citizen to keep this trouble away from you. If it happens that your GF does the same and her parents do the same then it further establishes that this guy is the bad actor. It also protects your guns against any claims on his part that you've threatened him. If you want to keep your gun rights don't throw them away on this guy.
Also, you've been told to get a restraining order against him. Follow that advice as well. The guy has threatened you. You have documentation of it. More importantly, you need to establish a document trail demonstrating that you did everything in your power to act as a responsible law abiding citizen to keep this trouble away from you. If it happens that your GF does the same and her parents do the same then it further establishes that this guy is the bad actor. It also protects your guns against any claims on his part that you've threatened him. If you want to keep your gun rights don't throw them away on this guy.