Spend some time "sharpening" her response to pressure. Make sure she stops, backs and gives to each side easier. Practice walking, with her head never in front of your shoulder even on a loose lead. When you stop walking she should stop. If she moves in front of you back her up behind you. She needs to learn she's not the leader.
With my horse I had a long firm stick, the one I used was a natural horsemanship style but a long dressage whip might work, or something. I'd run in lightly over her shoulders back until she got used to it. Then I'd start touching her on her back legs. At first she'd kick out at it, but because I was far away it didn't really matter. She got used to it touching her and stopped kicking, and I worked up to touching her back legs and picking up her feet.
Once they're good with being touched all over there, I also use a thick, long lead rope to pick up their legs from a distance until they're more accustomed to it.
Remember, the horse doesn't know she was abused or neglected. She's just an ordinary horse so treat her like an ordinary horse. Don't make excuses for her behaviour or let her get away with things because you feel sorry for her.