I read this and immediately thought of the "4 Boxes for the Defense of Liberty: Soap, Ballot, Jury, Ammo, to be used in that order."
In a Personal defense situation, could it not be also 4 boxes :Soap, Phone*, Ammo, Jury?
You did fine from a Legal standpoint, I think, but from a tactical standlpoint, the first inkling that an attacker should have that you armed should be a pair of loud BOOM!s...... you show him a gun and if he is armed and at all competent, he can draw and fire before you decide to do the same (Action almost invariably beats Reaction).
Call 911, and show him the phone. Get away from him ASAP.
*"Magic Elf Box"
TheGolden Rule of Tool Use: "If you don't know what you are doing, DON'T."