Would this accident have been my fault?

I was at a convenience store today and the exit of the store goes out into a lane where there is a stoplight, so there was a line of cars waiting at the exit and they were blocking me from being able to back out.
The car blocking my car saw that I was getting into my vehicle and pulled forward to give me some room to back out.

As I was backing out, a car came around the corner and honked at me. She kept moving as if to get into the spot that the car behind mine had opened up so I could back out so I had no choice but to pull back into my parking spot.
Otherwise she would have rammed right into me.

I’m positive that she saw that the car had moved forward to allowed ME room to back up because I saw her idling in her parking spot before I backed out, only when I started backing out did she start moving to get into the exit line.

When she passed my car I looked and saw that she was an elderly woman and she gave me a rude look like it was my fault.

I asked my parents and they said it would have been my fault if she had hit me.
I guess I just don’t understand that logic.