I kill this guy and go through court and depression over killing someone forever.
Nobody ever tells you what happens after you shoot somebody (actually, someone wrote a great book on it but it's no longer in print). Glad you brought it up. Yeah, you've got it on your conscience, and practically, you'll be in court of one form or another for the rest of your life. Yeah, you might have the legal right to shoot a guy, but the law still says his family/friends/employer/whoever can come after you for every last dime you have. And they will, even if "criminally speaking" you're totally clean.
If you're thinking "I need to bring a weapon to my practice space" you don't need a weapon, you need another practice space.

