The only thing I would add, is don't panic. If she does cut, and you see the wound, (eg: if she has an episode she does not hide from you & acts out in front of you) treat it calmly, with first aid, don't become upset. Separate feelings from actions, validate feelings, help her choose other ways to express the pain, fury, raging anxiety...
(this is likely what the t. is working with her on).