Dear LC:

I am sorry to hear about your difficult time in dealing with your students. Also, I am concerned that your director does not take your concerns and situation seriously. You should not have to tolerate or even accept any physical abuse from the students.
I know that if this situation was in a public school in the US, the law enforcement officials would have been involved in the situation immediately and the students would have been expelled and facing legal charges of assault against a public official (teachers are considered public oficials).
However, because you are in another country, their laws and regulations are not the same. My advice to you is to begin looking for another position at a school where you will have a caring director and the support from him or her in making sure the students show respect for their teacher, administrators and fellow classmates at all times.
Dr. Yanni Zack