I have disclosed to people I wanted to and felt comfortable with, in the natural course of a relationship. I had to leave work quite early to go to psychotherapy and did not see any reason to hide that. I was teased at work the next day, if I was having a good or bad day one of my bosses would point out I must have had a good or bad therapy session the afternoon before. As awkward and uncomfortable as that could sometimes be (when I was being snarly :-) I found it helpful as it was a great opportunity to practice hearing and using information on how I was perceived by others.

I would not tell someone so they'd know "just in case". I would never use my illness as an excuse for my behavior. Feeling anxious or being depressed, etc. makes it harder to behave in ways we'd like but never impossible and I always want to hold myself responsible for my own words and behavior.