Just take a break from her.. and wait it out come september. You don't want to ruin your horse.. he sounds absolutely wonderful.. and her methods are disgusting... :/ a head set isn't something you force your horse into.. it comes with their balance.. it's something they develop on their own!
And so what if she figures it out? You're asking for help, we give our opinions, if people have a problem then just deal with it head on. Be honest and that's that!