Are you still seeing your current T?
What exactly do you hope to get out of seeing this ex-T? Do you plan to just see him once or twice for closure?
Based on your previous posts about this ex-T, I think you might be taking steps backward by seeing this ex-T, unless it's only to find closure.
Again, based on your previous posts about ex-T, and given he did not acknowlege you in the waiting room, I don't want to you to get your hopes up that he will see you. I understand the terrible pain this could cause, and I don't think you deserve that from this ex-T. It would be great if your current T could help you find closure without having to do so with ex-T directly.
Keep us posted. Remember you are a valuable and worthy human being. Do not let the actions of this ex-T take that away from you.