The easiest answer is just talking about your traumatic memories with someone.
You don't even have to do that, though that's the better option, you can simply write out your feelings about the event and just let your thoughts flow.
I've been diagnosed as having PTSD and it took me a lot of therapy to really get a grip on my anxiety, paranoia, and nightmares.
From what I understand my therapist telling me, you have to expose yourself to the traumatic memories just enough to where you build up a mental tolerance of sorts. If you find it's too much at any point you can always step back and let your wounds close up a bit more before delving back into them.
Don't be aggressive about it, just be patient with yourself and remind yourself that you're safe now and that you are strong enough to overcome your past.
I recommend you find some form of professional counseling or therapy though, that is the best option. We're all just peers, not authorities on the subject. Take any of our advice with a fistful of salt.
