I understand what you are coming from. A lot of aspects of your story are similar to things I have experienced with past teachers. I've suffered from maternal transference my whole life and it could be very painful. I felt that way toward my T for a while...it started a couple months after I began seeing her and pretty much ended after I took a month off. The dynamics of our relationship changed entirely, but it was mostly a relief since the transference controlled my life.
It is important that you bring this concern up with your T, if you haven't already. It doesn't seem like it could end well if you keep this bottled up. Whether your therapist decides to terminate because she feels the attachment is unhealthy and harmful to you, or you end up going too far one day and are committed to a behavioral hospital, or you seriously hurt yourself...none of these things are good endings. You deserve to keep progressing and to feel better...don't let this stand in your way.
Maybe it will be very healing to bring this up with her and let her know about your history with your teacher. You two could start visiting where this may be coming from and start grieving the things you missed out getting from your mother and learning how to give those things to yourself. When you start to address the real issue that is causing this agonizing transference, you will find the attachment loosens its grip a little.

I hope you will consider it.