I fear the same things with T. I am starting to wonder whether "normal" people would not have the same fears and vulnerabilities, that they would not feel abandoned if their treatment provider recommended them to someone else. Like if someone had a physical health problem and was being treated and the treating physician said they could not help them, but knew someone who could - would the patient feel abandoned, hurt?
So maybe the very fact that this prospect does bring up issues, means that there are those issues to work on and the best person to address them is someone who is skilled in that area.
My rational head would totally respect the T for saying this, but I know that damaged emotional bit would find it so very traumatic and would feel all those things. Over-reacting? No I don't think you are, you are purely reacting to something that hits you deeply.

Soup