Can you get several interns from a nearby college? I'm trying to implement
school reform in an inner-city magnet school now also, and there are many
similarities to your story. I don't think the administration will "get it"
until enough good teachers leave. There is no reason you should put up with
situations like this!
You could threaten the psychologist/ administration/whoever that if the kids
are acting out you will meet them at the door and not let them in. It is a
privilege to come to art class. You should not have more than 24 in your
classes. Anyone who damages supplies/materials/furniture, misses art for
that day and the next with an automatic phone call home (which probably won't
I suggest you start looking for another job. After this experience, anyone
will hire you thinking you can handle anything -- which you can, by now.