I think one of the issues here is that your therapist's therapist has duties to your therapist as his client. He needs to look out for his other client's (your therapist's) best interests and that may include telling your therapist about his consultation with you. I don't think your privacy or confidentiality was violated under these circumstances because you knowingly went to see this "consultation" therapist, which seems on the edge of stalker-isn to me, like going to see your therapist's wife for a GYN exam or friending your therapist's contacts on social media or otherwise inserting yourself into your therapist's own zone of privacy.

I live in a small town and I know many people my therapist knows and sometimes she lets me know that she knows them. We have seen the same acupuncturist and I've taken a short class with her wife (didn't know it was her wife until after I'd registered, but she was fine with me doing so) and other connections. There's nothing wrong with having connections with people in your therapist's life but IMO a client should not seek these out, or if one does, it should be with disclosure to one therapist or the other. If you'd be straight with consultation T, you could have discussed whether he might feel the need to disclose that you were coming to see him with your current T and you wouldn't be in this situation in the first place.

This is just the way I see it and like the PP, you may feel free to ignore my opinion, it won't bother me at all.

I'm sorry. I'm not judging you--I'm judging these two therapists. Even more so that your therapist encouraged you to see his therapist.