Hey there Jess,
I definitely understand why you feel frustrated about the practice essay, don't worry. It makes total sense.
As for your real college essay, I don't think it's bad at all to write about that, and I don't think it makes you seem weak and unstable. The fact that you're working to overcome it shows your strength already, especially since you've been through such a traumatising experience. But it really all boils down to how you write it, and I'd advise letting a close friend or family member who already knows about your situation read it and see if maybe you've written too little or too much about the event in question. It's difficult to tell you whether or not it'll be good, because it depends on how you decide to write/structure the essay, but there's definitely nothing wrong with writing about this particular experience!
Hope this helped and feel free to
PM me if you ever need to talk!
Kyra