I would say, given her issues on the ground, you've got a lot to work through. She gave you ALOT of clues into how poor of a ride she was going to be long before you got on...(antzy, pawing, nervousness, refusing to stand, etc).
After getting her thoroughly vetted (if she hasn't already), I would start some serious ground work to re-establish some serious respect for her handlers. If you don't have a rope halter, use a bridle with a simple snaffle bit, so she can't lean on a flat halter. Work on lunging, with lots of transitions, get her bending, and flexing her head and neck, get her to yield her hips and shoulders, etc...with alot of ground work (atleast 30 minutes a day if you can) I am betting you will see a huge difference in a matter of a week or two. If she was a pasture puff for so long, that is your biggest issue here; she doesn't want to work, and she likely has little to no respect for handlers, due to not being worked with for so long. Go back to the basics and you will see some change fairly quickly.
As far as what you did (getting off and lunging her) I do not think you were wrong in doing this; As long as she was not untacked and brought back to her stall she DID NOT win her spaz attack...she still had to work, regardless of "how" she had to work. I probably would have worked her on the ground even longer than you did, just to really make my point that YOU WILL work, period, no questions asked!!!
When you do get back on, I am going to ask that you not simply walk her; get her feet moving...the more she has to focus on moving, the less she can focus on bucking, rearing, or kicking out, etc...so get her trotting and cantering, don't just walk!!! Walking is mindless, and enables a horse to 'think' about not having to work...make her work, and make her have a reason to want to stop and stand still.
"The ideal horseman has the courage of a lion, the patience of a saint, and the hands of a woman..."