Wow-- I'm sorry to hear that. That is, simply put, unacceptable.
I would suggest you take two courses of action:
(1) Call the police and file an incident report. It sounds like what the teacher did is battery, and the teacher could be liable for criminal sanctions.
(2) I would find and retain a local civil litigation
attorney. Civil action
may be appropriate in this situation (especially if this teacher has a history of such behavior, which she may or may not have). Nonetheless, the attorney will need to do various actions, such as provide notice to this school of this incident in order to preserve your right to file a lawsuit, and at the very least, to ensure such behavior does not happen again. If the attorney does suggest filing a lawsuit, the attorney may also seek punitive damages
Beyond that, many attorneys offer free consultations, and they would also take a case like this one on a contingency basis-- that way, the attorney would only be compensated from a portion of a settlement or judgment obtained, and you wouldn't have to pay for the attorney out of pocket. If you do want to find such an attorney, your local bar association will be a good resource.
I hope this helps, and please let me know if you have any follow-up questions.