If reporting her isn't what you want right now, that's okay. You are under no obligation to. But there may come a time when you feel ready to, and when it might help you, so it might be helpful to just put that idea on hold.
I had the exact same desire to send my first therapist a letter and I even posted an anonymised version on here and asked whether I should send it.
The advice I got was very good - I was invited to consider my therapist's response. How would I feel about no response? Or an argumentative response? (The latter could have drawn me into a dialogue with him which would have been bad)
The one line that sticks in my head from that thread is "it's not possible to disengage by engaging in this way" (feralkittymom) and ultimately she was right. I had to disengage and move forward, and I have, given time.
If I was able to report him, I am now at a place where I might consider it, however he was not a member of a professional body, and it's not a licenced profession in this country, so there's no one to complain to. It is worth holding on to the info you have in case you want to report in future.
Sorry things have been so terribly tough for you. Wishing you healing.