Was she spelled after her time on the track? How long has she been off the track?
My warmblood gelding was exceptionally buddy sour when I purchased him. My agistment owners forgot one morning to now put him out last, and he attempted to jump the stable door and hung himself by the stifles.
I found that while handling him, the best option was to ignore the behaviour. If I reacted, he would get worse. Put the horse to work, as soon as my boy would start to neigh, pace and jig around, I would start making him yield his quarters and shoulders, back up, leg yield in hand etc. It was a good tool for me as he would HAVE to concentrate on where his legs were going and forget about carrying on like a pork chop!
Under saddle he was fine, as long as he was busy.
For paddocking, I found that changing paddocking arrangements around helped a lot. Some days he was on his own but next to another horse, other days he was in with a small herd, and once he got good enough to stop trying to kill himself pushing through or jumping fences, he went out on his own with a paddock between him and the other horses. By changing it up, he stopped getting hugely attached to one horse, and began to settle. He got used to different horses coming and going.
Unfortunately my boy wasn't driven by food, but if your mare is a bit of a foodie, you can try giving her some hay when you take the other horse out to distract her.
Regarding tying, leave her there. Don't give her the time of day when she paws. As long as you tie her somewhere the she can't damage too badly with pawing, and tie her solidly to something that won't pull away so she can take off with a pole attached to her head, then she can just stand there and paw to her hearts content.
Once again, my boy did it, and in the end I left him standing for half a day. I cleaned tack, cleaned stables, cleaned my paddocks, worked the youngster and by the time I was done, he was snoozing happily. He was MUCH better after that and settled very quickly. Just make sure you are around the vicinity so if the proverbial hits the fan you can go in there and 'save' her.
If she pushes you when you lead her, don't allow it. Personally I wouldn't discipline in the form of voice and a whack in this situation as it can flare the anxiety. Instead, stop, back up, yield away from you, and walk on again. Repeat every time she pushes into you. If she's got a few brain cells in that noggin of hers, she should work out pretty quickly that you're not going to walk any faster if she shoves you.
With the loading issue, how are you loading her? What technique are you using?