Understandably, it is difficult for your friend to return to school. It is the location of several traumatic incidents. The school has become associated with those events. It makes sense that she had the negative reaction you described.
Your friend may need more help than you can offer. She may need to see a mental health professional. She has endured several traumatic experiences. To help her go back to school, help from a counselor would be a great place to start. Perhaps there is a counselor at the school she can speak to.
If she’s not willing to see a counselor then perhaps you and several other friends could act as a support system for her. If she feels anxious about entering the school perhaps you could be by her side when and if her anxiety increases. You could do this by reassuring her that she is safe and that you are there if she needs emotional support.
As I mentioned above, because she is having panic and anxiety about entering the school, professional help may be necessary. Suggest that she seek counseling. Your friend is lucky to have such a caring and supportive friend. I wish you the best of luck. Thank you for your question.