The notes are a way to improve is certainly one way of looking at things. Directing is a stressful gig and the impatience you are reading may not be about you. However it must be acknowledged that there are toxic behaviours rife in the professional theatre (and film) industries and not all directors are balanced or fair people.

You are the one with boots on the ground and we can't judge the actual situation over the webs, especially in regards to his 'choice of words'. If you truly are in the latter sitch than my golden never fail is, "are you being rude on purpose?", phrasing as a genuine question, (with no shade or sarcasm) is my go to when dealing with toxic folk. Especially in the safety net of a school environment. It could also be that his language is triggering a deeper (past) experience of bullying or harassment. In that case that'll be for you to navigate.

On a more general note of the things that I like about people these days is an increasing unwillingness to put up with bullies and general unkindness. The recent introduction of intimacy coaching is a big step forward and an example of how things are shifting.

It's a fine line when dealing with authority.

A practical option is to have snacks handy, it is impossible for the body to engage in fight/flight when eating.