Years ago, I was accused of "consciously starving my baby" by the nurse assisting my doctor. I was very concerned and offended by her comment. The teacher of the baby class I was taking told me to report it to my doctor. When I did, he had the nurse come in so I could officially identify her. I found out from my new doctor that the nurse was fired that day.
In the meantime, I was advised to gather quotes from friends, neighbors, family, a variety of people who would witness my character on paper. The gal teaching the baby class had been a nurse for 25 years and cautioned me of the "take your baby, ask questions later" attitude of Social Services. This scared me to death, but I did what she said and Social Services never came to my door.
My advise is to document the attitudes of those you've encountered at school, report the guilty attitude and actions of the school to the school district and cc the principal, meet with your son's teacher and get her personal view - if good, get her to write a supportive letter for your records only (assure her the principal won't see them or she may not provide it for you for fear of losing her job), . . . basically, gather as much supportive documentation as you can before you leave. Once you arrive at your new school, have a professional letter ready to present for your records, in case the present school has dirtied your reputation.
I've been a teacher for eighteen years (taught in both public, private, and home education).
I've seen a lot, been a part of a lot, and prayed to God through it all!