You did far better than I would. I would try to kindly ask her to cut that out, in a 'dude, what the fuck' way, I'm not good with dealing with other people's emotional problems, so I bet it would sound out rude.
At least she had you to vent and slap her back to her senses before anything went out of control. I think that is worth at least a banana sticker.
Underlated edit: I just noticed the last 4 posts (including me) have catgirl avatars.