Dati rin akong professor at nakaranas na rin ng ganyan noong baguhan pa akong nagtuturo, but in a different way. Inipit ko kasi sa pader yung isang barumbadong estudyante ko; anak pala ng Dean he he - siyempre nagalit si Daddy at naglabas ng sama ng loob, pero I stood my ground. Everything went well afterwards - at my license pa akong ombagin siya kapag umulit ulit he he.
Kidding aside, parehas din yan sa kumpanya, you'll receive the worst words in the field or in the office. Kung mahina sikmura mo, ganyan nga mangyari like sa kaibigan mo. I know, everybody is different, but you need to learn to defend yourself in any way you can - that's reality.
Sa sitwasyon nya, since ayaw naman ng kung anong aksyon, best advice is file a temporary leave of absence (for a valid reason). Follow-up again with another similar letter if summoned, then send a formal resignation... and then never return. Wala ng saysay yang contract mga iho kapag ginawa mo yan. They already adjusted their schedule during your absence till you finally resigned. Use logic if you don't have the guts to fight back. It's the safest way based on your friends' qualities.
Magbakasyon siya muna to recover and mature, then try his/her luck again.
PH