Thank you so much for the feedback and especially Cherie who has helped me to realize that I could not have done much more in the situation we were in. It did feel very close to a full rear!
Now to give more history. The person that was training the horse did not start the horse, but was asked by the owners (from a ranch) if she would like to get her going further in dressage. The first trainers, who broke her, were the ones that should have worked her more on going out alone. My friend did a good job getting the mare on the aids, but that was all she was asked to do...so little did she know that this horse had an issue with going out alone.
That said - No I can't send her back BUT I do have access to amazing trainers where I am.
My coach is a Grand Prix rider from Germany who grew up on a breeding farm and started many youngsters. She is going to meet me at the barn tonight and we are going to work on this. She assisted me in hand the other night and we got her walking out off the property (in pitch black & fog!) with very little fussing....so it is a start.
I also have the option of many old 'babysitter' horses in the area. We are a tight knit community outside of Vancouver BC and I have a zillion resources.
What I needed to know was whether I could've done something differently in that moment.
But I will back up and slow down and start with some basics.
The one good thing I can say about her is she is never really a scary mare, no buck, no bolt, etc. So I don't worry about falling.