Without you SPEAKING UP to this person, EVERYTIME, things will not improve. Muttering to yourself, stomping out of the arena, obviously has not changed anything. She is oblivious to the situation. Using your horse as a stop means you need to get protective or let him turn into a kicker when horses approach from behind. Do you WANT that to happen, letting her wreck your horse’s training? Break into her attention, talk to the BO about problems!
If you do not act in these instances, then you should shoulder the blame for things staying the same. Like with a pushy horse, GET HER ATTENTION, then state the problems she is creating. Otherwise it has you coming off as passive/agressive, crabby attitude, while she remains clueless that SHE is causing trouble.
Her horse is evidently trained to go where aimed, regardless of things in the way, no sense of self-preservation. So do not expect him to try avoiding you. Without changes, she probably will end up riding into you, maybe knocking you over!! Seen that happen. Won’t be “her fault”, you should have got out of the way!!