Quickest I can think of is probably cyanide, mix advil, ibuprofen, or zquil if you want no pain. You can probably find a guide to obtaining them somewhere. Most fun that's easy is probably speeding down the highway with a car full of napalm at night, getting the cops on you, and crashing the fucker (or lighting a match).
But, as >>544441
said, get help. My step-dad has ptsd as well. He's still alive. Goes to support groups every month. You can get through this. You're not alone.