I would be very suspicious of both their motivations and intentions. Therapists are not supposed to hound clients and to empower them to know when they want to quit and stay and to be ok with their choices around that.
A part of this therapist probably is excited because she has never encountered a client like you and views this as great learning and also her motivation comes into it. She sees a great piece of research here.
I would politely decline and never contact her again. This behaviour of hers is unethical because firstly her main interest should be a duty of care to you, her client and I don't see that here!
I agree with Growly, fetishes don't go away and the work is to explore how you and your partner can live together with the fetish. How can your needs and your wife's needs be met. This could mean a great deal of negotiation between you but once you both understand what it means to you both it can be managed