^ I agree! That's just sick and cruel....
Your mare is without a doubt headshy. It's not necessarily anything that you did, but it may have been something that happened before you owned her.
The worst reaction to this is to try and force the issue. It will make the problem even worse.
What you should aim for is to let her realize that it's not such a bad thing to get her ears handled. Work around her face (not too near her ears yet) rubbing her and when she lets you do this without pulling her head up, give her a treat or reward of any sort. As soon as you can do this with no hassles, go to her neck and rub her gently, rewarding her when she stays calm.
As soon as she's fine with all of this, start rubbing her poll area VERY gently, again rewarding her when she accepts it. When that's going all good (remember that this will take alot of patience and time) move slowly to the base of her ears, working gently until you can touch her ears without her freaking out.
As I said, this will take ALOT of time, but in the end it's worth it. At the barn I'm currently at, there is a very sweet mare that used to be VERY headshy, but over time you can now put a halter on her and scratch her neck and even rub her face a little.