Well good luck to you! It's hard to fix a horse that has been spoiled by others. Horses can be very pushy and hard to deal with when they are not handled appropriately! But the biggest thing is that you have to be very consistent with her and set very clear boundaries. I think that if you work on her tying out every day and also work in a round pen you will make a lot of progress. When you are doing the saddle excercise in the round pen you have to be prepared to put the saddle down instantly and ask her to work the moment she moves out or makes any inappropriate movement into your space. She might get really tired, and you will probably get really tired, but this is a battle you have to be committed to win each and every time you do it. Make sure you keep a dressage whip or a lunging whip handy to keep her out of your space as you're asking her to move out from you. It sounds like this horse could really benefit from some round pen/ground work in general! I've found that ground work makes such a huge difference. I'll be honest...I hate doing it, but I have a horse that will test his boundaries all the time and look for holes in what I'm doing. I find that putting him in a round pen and working him once a week or so really keeps the balance in check for him and he looks at me more as the boss when I'm consistent with the ground work.
Best of luck and keep us posted!