I can relate to being anxious/unable to sleep prior to any big day (first day on the job, night before any big trip, et.) but not PTSD, dissociation, and hallucinations.

It's OK if your other friends find out about your issues--maybe this would be a blessing! That you do not want to burden anyone with your issues makes your burden that much harder. Maybe working on opening up to more of your IRL friends would be helpful. You need all the help you can get and your friends probably want to help!