That's a really tough situation to be in.
On the one hand, if you piss someone off enough, he will break, plain and simple, especially if he's already emotionally unstable/unreasonable, such as this fellow is.
My advice is proceed with caution.
If you indicate in any way that you will retaliate with this guy, including plain ignoring him and playing guitar anyway, he can have you arrested for AGGRAVATED HARASSMENT. This is a booking offense and you might spend the night in jail. If he decides to press charges, you WILL have to go to court over it.
If this guy is in the least bit law-saavy, you could have a MAJOR PROBLEM ON YOUR HANDS.
Even if you try to explain to the police you're in the right, they will not want to listen to you. They will want to fill their quota, especially if this guy is pissed to the point of pressing charges against you. You will have to wait until it goes to trial to plead your case.
Once again --
proceed with caution!!!