Once at the beginning of therapy I brought in some notes about my feelings. I was struggling a lot with disclosing things so I just read half of the list, then I put it on T's desk while paying and later in the tube I realized I had left it there.
The following week I asked T if she had seen something and she said "Yes. I have it, don't worry". I felt horrible, but now she knows far more than what's written in there (and also has many other interesting things from me, lol).