confidentiality issues , what shall I do as a client?

I visited a therapist a while back and they used to tell me a lot about their niece, who works in the same field as me to the point I was able to recognize who that niece is, and we were coincidentally once put into the same group. It was the most awkward thing bc I recognized him & it seems like he recognized me too although we don’t even know each other .. and now there is this silent tension where I don’t speak to them or come near them. How shall I deal with such thing?