That is a horrible response. Maybe she was surprised and caught off guard. One does not need to be told "I am a heterosexual and in a relationship". She should have seen "your shame". I am going to tell you what my t said.....maybe it will make you feel better---

"This is not an abnormal thing to happen in therapy. It shows that our therapeutic relationship is good. It is going to be ok. It is ok for you to say your feelings. Feeling this way is understandable given your childhood. It is to be expected. It is ok. It is ok. It is ok (repeated like 8-9 times)."

The above was not said all at once but over the course of some time dealing with erotic/maternal transference.