I've experienced both paternal and erotic transference toward the same therapist at different times (sometimes at the same time)--and this has happened with two different therapists, who are very different both in personality and appearance. It's actually relatively common, from what I've read and been told.

I tended to view the erotic feelings as more wanting connection with the therapist rather than actually wanting something sexual to happen with them. I found that if it tried to push the thoughts away, it could make them more intense. So I tried to just accept them, like, "OK, I'm feeling this. I know what it's about, and it's OK."

As for whether to tell your therapist about them, that's much more complicated and would depend so much on your therapist and their comfort level with and experience with this sort of thing. It may partly have to do with their therapeutic orientation, too (like humanistic vs. psychodynamic vs. more cognitive or something else). I've had very...mixed results (including with the same therapist at different times) sharing both paternal/maternal and erotic feelings.

The main thing to keep in mind is exactly what you said--once you say them, you can't un-say them. My current therapist has said (in general, not about me specifically) that once that sort of thing is shared, it "lives in the relationship." You might be able to talk about that sort of thing in more general terms with your therapist, but I'd avoid sharing specific erotic thoughts. Others may feel it's better to get it out there, but it's very much a risk.

Hope that helped in some way! Just know you're not alone in this.