You obviously have to make your own decision, but I have done extensive searching similar to what you did.

It has not come up in therapy. But my T knows that I never even went on a date with anyone until I did a thorough background check -- court records, previous addresses, tax filings, social networks, you name it.

So, T knows that I'm the Googling-kind. She can assume that I've done the same to her.

She hasn't asked and I'm not telling. If she did ask, I think I would just say, "Of course I did an extensive background check on you. I didn't find anything to suggest that you were not trustworthy."

Because honestly, if you get to the root of why you are searching it is probably this 1) to feel safe and 2) to feel closer to the therapist.

Neither is bad. I wouldn't be able to share the most personal details of my life with someone unless I knew where that person lived. That's just me. Others don't have my hangups.

Google searching isn't unethical and it isn't against the law. I think you only cross the moral-line if you lie or misrepresent yourself to obtain information. That's wrong, as I see it.

Edited to add:

I guess I haven't told T because:
--It hasn't come up

--I don't feel guilty, thus I don't feel the need to confess

--I don't see it as wrong, thus I don't feel the need to confess

--I have a clear conscience about it

--I don't want to spend precious therapy minutes talking about what of T's personal life I have discovered

--The content of our sessions is the issues I need help with or want to change. Being an extensive Googler is not something about myself that I wish to change.

--My T is not the only person in my life whom I've gathered information on. It's common behavior for me.

It may be worth exploring someday why I feel so unsafe in the world that I prepare dossiers on people before letting them in. But it's a remote issue for me.