Your thoughtful and detailed question opens the portal to the dynamics of therapy. It is always difficult to have clear–cut answers and decisions. There are many different therapeutic approaches and avenues of healing that take very different paths, and the ethical guidelines are designed to help manage the parameters that therapists operate within.
The clarity of the boundaries in the relationship as it is being discussed is certainly an important feature of a healthy therapeutic connection. At the core of most successful psychotherapies is the relationship between the therapist and the client. The concern always is the balance and limits of the relationship that need to be respected.
I would recommend three things: First, keep talking about this with your therapist. This will keep the issue on the front burner. Iinclude in your discussion that you have even questioned the degree to which she can maintain the boundary. Talk to her about the fact you are considering ending therapy because of these feelings. A therapist with 30 years of experience is likely to have traveled this road with others and should be able to navigate this with you.
Second, I would consider joining a group not run by your therapist. A dynamic group will allow your relational dynamics to be more fully explored with others under the guidance of another therapist. This will help keep the perspective on your continued growth and well-being.
Finally, keep talking about this and don’t feel like you have to keep your concerns and feelings a secret. Thinking that you cannot talk about this would be something you want to monitor and guard against.
As with any human relationship open communication is essential. I applaud the fact that you have written this letter and want to keep your therapy going in the right direction. This now involves you speaking up and bringing the issue into the therapeutic relationship itself. If you feel the therapist isn’t able to manage this then you may have to move on. But this can also be an opportunity for growth, clarity and individuation.