almost HAD TO USE MY GUN today

[dfinch]

It was 6:47 this morning and I had just arrived to work (accounting), parking as I usually did in the multi floor garage. I am typically one of the first people to arrive so I found it odd that a car pulled in a few spots down from me. Red, two-door coupe with tinted windows. As I stepped out of my car (with my Glock IWB strong-side) I immediately checked my 1,4,8, and 11 o'clock and slowly began to walk towards the building entrance making sure to give direct eye-contact and clear my throat very loud to make sure the shady character in the red sedan knew that I knew that they were there. As the door opened to said sedan, a woman, 5'10 dressed in a pinstripe skirt and white blouse stepped out of her car. The strange detail that upped my alert to orange-red was the fact that she was carrying a messenger bag that was clearly made for a man. As I got closer (she had parked between my car and the entrance) she looked at me and said, "Good morning", to which I held out my hand as to let her know not to approach any closer and said "GOOD MORNING!" politely but loud and firm enough that she knew that I wasn't going to be a victim. Her smile faded and she looked somewhat confused. As I continued to the entrance (about 20 yards from where I park), I could hear her high-heeled footsteps behind me. This made me extremely nervous so I pulled out my cell phone (left side pant pocket) and pretended that I was receiving a phone call, "YES DETECTIVE?" I said loudly, stopped walking and veered to the left without ever dropping my SA until the woman passed me. As she passed, she was looking straight ahead towards the entrance of the building as I never stopped looking right at her intently with my right hand resting slightly on the butt of my Glock 26 holding my breath. After she was about 20 feet ahead (at this point she was walking with urgency), I exhaled a sigh of relief and continued on.
After the entire morning at my desk replaying the encounter over and over again at work, I began to think about the WRONG things I did in that situation:

1) I should have never exited the car before checking my surroundings and waiting for the person in the red car to exit first, making careful detailed notes on description, facial features, and other key distinguishable traits the shady person may have had

2) NEVER should I have let the shady character get into my 6 o'clock. I should have immediately turned around confidently and continued to make contact until said person passed making sure she knew that I was gathering information that I may need for the authorities.

When i got home that evening, I went straight to the garage and practiced my draw and SHOUT techniques as well as my roll, somersault and aim drills and made myself a promise that I would never ever be caught off-guard again.

Thoughts about how I should have handled it?

Cliffs:
-Pull in to work
-Suspicious vehicle and suspect in parking garage
-Suspect ends up behind me (failure on my part)
-I think about it all day long
-Go home and practice roll drills / somersaults