Actually. My mom outed me to a lot of my community as well. Not as badly as yours though. I'm terribly sorry that happened. I... I would probably skip the trip mainly because I would be livid to the point that I wouldn't want to see her at all and wouldn't want to go there and face all the people she's told and would be afraid I would say something terrible to her. Just by you telling her (either by email or phone or face to face) that she really crossed a line and you're very upset with her for now should get the point across. She needs to understand that while she found out about your depression, it is YOUR depression which means it's your decision of who to tell and etc.

Of course, if you have a lot of other reasons to go back to that area, maybe it would be worth it to go back but still, the most important part is to tell her how much you've been hurt by how she's told everyone and how it is not her issue to tell. Especially for something so personal. Ugh I would just be soooooo angry (I'm getting twitchy just thinking about it)!

Best of luck!

Edit: The most important part is to consider yourself. Will it cause a ridiculous amount of anxiety and trigger something if you go? Do you think it's worth it to face the issue head on or let it steam a bit before meeting?