One way you can look at this, is that you tried something, it did not work for you, and now you have more information. No failure in this, just learning.

She truly might be someone with which you cannot have those type of in-depth conversations with, at least for now. Since she attacked, please keep this fact in mind, so you can weigh how much you want to deal with her or not.

Since she has kept her mental health issues front and center consistently in your friendship, perfectly normal that you would at some point say something. Would she be willing to help you shift the friendship to doing fun things, to not hashing out mental health stuff?

Ideally the deep type of support I think needs to come from a therapist, someone paid, a health care person, your friend can keep the stuff for there, appropriately. One friend cannot and should not be everything. You don't have to be her therapist, her counselor, her cheerleader. And you get to say No and not like things.

Hmm, if I had someone come to me with what you had said, I'd be surprised cause I don't see myself that way. I'd work to keep both of us on track, not use attacking language, work together to find out what is at the core of things. If I found out that I had indeed been talking way too much about my mental health stuff to you, it would hopefully dawn on me that I need to get myself back into therapy. That I need to work in my journal and find other ways to vent. I'd work to figure out how both of us can win. I'd probably end up in tears and I'd apologize if I figured out that I had indeed been out of line. If our friendship came through intact and stronger, I'd suggest going out and doing something fun!

You get to be angry, you have the right to your feelings.

Ultimately, I would say you did not force her to be triggered. Might be a triggering situation for her, but she has lots of choices. She could have walked away. She could have worked to be quiet and really listen to you.

These are just some of my fast thoughts on the subject, just my humble opinion. I hope that no matter what, you take good care of -you-.