I effing hate that crap. No respect for their fellow man. You did everything right except for one thing you did out of order. This is what you should have done first...
begin to put distance between me and the group
I have a conceal carry permit and one of the things I was taught in my training was how to avoid having to ever pull my gun. Avoidance. If I go to a drug store and there's three unsavory types standing around outside I simply go to another drug store or come back. I don't believe in vigilantism I don't believe everyone should own a gun but have you given thought to getting your CCW permit?