Hi. So sorry you are feeling like this, but it IS normal. You are bound to be anxious that this might happen again. A few suggestions, write to the school and SEN governor. You can state how happy you are with the new teacher, but you are concerned about past events and state what happened. You can ask for the schools assurance that this will not be repeated. Also if your child is involved with CAMHS, then you should be able to speak to someone there too. That service is for the child AND their parents. Lastly, draw a picture or write a letter to the person who is annoying you most, then tear it up and throw it away.
Hope this helps