Sadly, there's an uptick in mental disorders since the advent of this pandemic, and, like many hospitals, therapists are getting overloaded with patients. Some have quit their jobs, others have taken on more clients than they ever have in their lifetimes. There's not enough therapists to meet everyone's needs, though I think everyone could at least use an annual mental-health checkup and an appointment as needed.

You really should have continuity of care, and that facility should have found you a replacement therapist. Waiting 3 months for a therapist to return is not stable, and it's better to find a replacement now than to keep you hooked and waiting for 3 months - only to find that she's not returning, etc. And even if she does return, would you feel comfortable and stable sticking with her? What if she does this again and again? I would see that as a red flag, and if I knew that therapist in real life, I'd say to her to find a different profession, such as research in psychology or a profession out of the field, if it's that triggering to her to cause her to have a 3-month sabbatical.

You could also report her and the institution to the psychology board where she is licensed. She's supposed to report her mental or physical disorders to the licensing board and to claim that it is being managed enough for her job and to not interfere with her job. The fact that it is interfering with her job is troublesome at best, abandonment at worst. She did little to ensure continuity of care, and her unethical statements and response border on abandoning you unethically as a client. I would report her to the licensing board so that she can tell them whether she should remain licensed to practice or not.

Meanwhile, can you find a different therapist from a different institution? It seems like that institution dropped the ball on you.