Welcome to the site.
I am a psychiatrist and i believe i can help you with your query.
Well, first of all let me say that it is quite natural for a person who is in therapy to transfer his feelings, memories, perceptions, experiences of past which may be related to a person like it is in this case your feelings associated with your ex girlfriend, onto the therapist. So while it is normally expected for patients to develop transference in therapy sessions but this transference needs to be expressed to one's own therapist so that a good therapist instead of developing counter-transference towards the patient which will ultimately compromise the therapy, he / she will like to address the core issue and help the person to come out of transference and help the same to resume a harmonious therapeutic alliance and rapport between self and the patient.
So in simple words, i will like to encourage you to express your feelings about transference to your therapist so that you unburden yourself of these emotional upheaval and give a fair opportunity to your therapist to deal with transference in her own professional way without letting the therapy to derail. Usually therapists are well equipped to manage transference issues but that can only happen if you earnestly explain your situation to them , so let your feelings come out and share with her your thoughts after all that is what forms the core basis of therapy wher the therapist need to unearth even the most discreet memories, thoughts which the person tries to resent or is reluctant to address because of the fear of revisiting an agonizing phase which those thoughts and memories have been associated with.
Lastly, i will also like to mention here that by addressing this transference issue you may find a closure to the past emotional trauma that is associated with your ex girlfriend which eventually may bring an ultimate peace to your mind.
I hope this makes sense and gives you an insight into what you can do from here on.
Wish you all the best.
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