I think your T is WAY out of line and handling this very poorly. I honestly don't think I could continue to work with him because of this alone. But I undersatnd attachment and how hard it is to start over. I think you have been very articulate about the way it makes you feel and compelling in your arguments.

My T and I have a community in common, and we just handle it like adults. We talk about what to do if we end up in the same place at the same time, we talk about relationships we have in common and how to handle that, sometimes we do therapy around it if it stirs up stuff in me. Dual or overlapping roles are not inherently unethical--they just need to be managed so the client is not harmed. That is the most important thing here, that the client is not harmed. And it seems to me that either of the options he is offering could cause you harm (you are either denied your community or you lose your T).

Once my T and I were in a situation where others in the community could get something from T that I thought I wouldn't be able to get because he was my therapist. When I told him this, he said that clients are not supposed to be harmed from dual roles, and it's the therapist's job to ensure that doesn't happen, and that denying me something that other people in the community got because of our dual roles would be unethical. And so I, too, got this thing that others in the community were getting from him.

(As I write this, I'm finding that I'm quite mad at your therapist. He's being a jerk.)

I feel like I should add, maybe there is nuance to this that would make it impossible/harmful for the two of you to be both members of the same community and therapist/client. I suppose that is possible. But generally, in most circumstances, I think both should be possible