I have this friend, and I kind of like her, but we're not thát close. We only have a few lessons together, but when we do, we talk a lot. But recently it came up that her mental health isn't that great. She has huge social fears and she's now going to a psychologist/psychiatrist. I don't know if it would be a great thing to talk to her about something like liking girls (in general even), because I'm afraid she'll just withdraw...
It is possible that she will react negatively, but I doubt her mental health would affect how she views anything LGBTQ+ related.
I don't think your sexualityor talking about sexuality in general would cause her to withdraw at all. I have a couple of friends with anxiety disorders and if they're comfortable with you then it tends to be fine. If she does react negatively then its extremely unlikely to be due to her mental health.
