Well, unfortantely your mare really needs to learn to be tied. It's one of the most basic, but fundamental, things your horse needs to learn.
I can suggest one of two things - Finding one hell of a post to tie her too and let her fight it out.
Or, you can right something around her elbows so when she pulls back she actually squeezes herself and she'll have to go forward to relieve the pressure. If you do this, just make sure you use a large cotton rope to make sure you don't have any rope burn.
I've dealt with many horses like this (just sent one home, actually!) and believe I know how frustrating it is! You really need to have the patience of a saint and there have been a few times where I've just had to turn my back for a few minutes to relax. Don't leave, just turn your back and take deep breaths. I find this usually works to help calm and antsy horse. And myself.
Now, your mare has developed some very dangerous behaviour. It only takes one time for her to step on your foot, push you over with her shoulder, and then your trampled. She obviously has no regard for your personal space and if she spooks another horse behind you he probably won't either.
This seriously needs to be addressed before either you, your horse, or someone else gets hurt.
Please don't take that to mean you haven't done anything to help her or yourself; I realise that you have. I think it's just time to put on your boxing gloves and git'r'done, so to speak. ;)
First exercise I will suggest, aside from letting herself freak out while she's tied, is softening in the halter and/or bridle. I had a horse who, being 16.1hh, throw his head up and me, being 5'2", was literally hanging, and it was NOT COOL!
Start with the halter and gently apply pressure straight downwards with the lead rope. The SECOND she drops her head, no matter how miniscule, release the pressure and let her be. Continue to do this until as soon as she feels the slightest pressure, she will automatically drop her head.
Again, this helps when you bridle because you'll use your hand where on her poll where the halter puts pressure on. When she feels this pressure she will drop your head. It won't be quite as effective as the halter until she gets the hang of it. It took my gelding about three days to figure it out, but I practiced with him several times a day.
Another thing that I think would help her is to learn to wear hobbles. Believe me you, she will have a whole new idea of respect of her freedom once it's taken away from her. An indoor arena makes a great, safe place for this.
Please remember that once you have the hobbles hooked up, you need to get your butt out of there because she is going to have a hissy fit. Most times, they lunge forward with both front feet in the air and because you're there, you need to move quick!
Another thing I can suggest is what I suggest for ChevyPrincess, and that's getting her to learn her backing up, sidepass, spins, and turn on the forehand from the ground.
Walk beside her and the minutes she passes your line, stop and push her back. Don't be nice about, don't plead with her. Use the end of the lead rope on her chest if you have too. Push her back until she doesn't want to go back anymore. This motion of her wanting to stop is great for her because she's such a foward horse. She will eventually learn that the minute you stop, even mid-stride, she is going to have to either stop, or back up quickly.
If you can get her to stand still long enough, you can use the finger pressure on her chest to back her up and make her realise that she cannot invade your personal space.
Same with getting her to move sideways. Keep the lead shank loose but snug, use your hands to ask her to move over. Again, the minute she moves over step away from her and let her think about it. If she doesn't respond or invades your space, get after her.
Your mare, right now, is the domiant one. You need to turn that around, and she isn't going to like it. You are going to have to be aggressive with her, just as she's being aggressive with you. I'm not talking about harsh beatings, I'm talking about educated, trainable discipline.
Anyhow, I hope through all my rambling something I've said will help you!
Best of luck with your mare, and if I helped, don't hesitate to aks anymore questions! :)