Traumatic or otherwise difficult experiences do NOT have to be off the table for your college application essays. They are legitimate subjects (depending on the essay prompt, of course; it has to make sense as a response to the particular question).
The key is to remember that the ultimate topic for any college application essay is YOU — not the trauma itself. You don’t want to spend too much of your precious word count on a blow by blow description of what happened, because then you’ll run out of room to talk about the more important part: your reflection.
So keep the description succinct, and focus most of the essay on your reflection on the experience and what that has meant for your own development.
In terms of signaling: ideally your writing and reflection shows that you had a post-traumatic *growth* experience (you don’t have to use those words, but you do want to show that something meaningful came out of it), and that you’re not stuck in your life in a way that would prevent you from thriving in college and moving forward in a positive way. Admissions officers have to worry a lot about who is going to thrive or whether they are just setting people up for failure, so try to read your story from their perspective; what does it say about you going forward? Is the impression you’re giving them what you want them to take away about you?
Hope that helps! Good luck with this next, big step!