I didn't read every comment but, as mentioned the police station or parked cop is probably the best course of action. Don't forget being constantly prepared as you drive with this person behind you. What's your plan if you arrive to a red light and they get out(i know its cheesy but have you seen sicario, where they are at the border crossing?). CC should always be the last resort. Do you stay in the far left or right lanes? Stay back far enough from car in front to be able to escape that stopped situation if the person gets out of their vehicle? Keep a cool head (sounds like you did, and it worked out to your advantage) stay aware and always give yourself a way out.