Yeah, that is unfortunate... Unfortunately most of the scenarios I've had similar to that, are just as horrible (I think)... I dated someone online, he thought I was cheating on him (which I was not), but he was okay with my trans status and I had him promise not to tell anyone about it. We both met in this IRC server that we went to concerning a certain topic of interest/hobby, and he started bringing the drama there. I requested to have him banned since he wouldn't be quiet and kept starting stuff. They kicked him from the server, and he came back and broke his promise and told everyone there (quite a few people) about me in the public channel. It was quite devastating, I was heartbroken not really because those people knew about me but because he had promised me he wouldn't tell of it... I almost went to a psychiatric (mental) hospital because I was so suicidal.
But I usually try to tell people about myself before I get too involved with them, it saves some heartache, but it still hurts when they reject you over how you can't help feeling.