Hmmm.

Dear Georgina,
I am bewildered by your message received yesterday. Having talked at length to Mrs Blank and Mr Blank last summer, I clearly recall inviting you into school to meet with us to go through your concerns. The bitterness of your messages clearly indicated that nothing I could write was or is likely to change your feelings.
However, the invitation remains open and I hope you might still take it up given that you remain so upset by your experience. Feel free to ring me on 00000 000000 and I will arrange to meet with you at a mutually convenient time. It would be my view that you need to be able to put your feelings behind you and I think a discussion would be the best way of achieving this.
In the meantime, best wishes for your current studies.