"Firing" is such a harsh term. To me, "firing" suggests the employee did something wrong or was seriously unsatisfactory. Maybe if you just look at the change as "moving on", it would make the transition easier.

Do you think you will talk to your therapist about making a switch before you make the final decision? Sometimes when we let our Ts know that we are stuck and not getting much out of therapy, they can help with that. I think especially if you have a 2 and a half year history together, it would honor the relationship to share your thinking with her.