I read your post, and even tho I have not been in war, I suffered PTSD for 25 years due to childhood sexual abuse. I know exactly how you feel, the highs and the lows, the feeling of despair, of when is this all going to end, the hopelessness, the depression. There is help and if it fixed me, then it will fix you.
You need to find a PTSD therapist, one who specializes in PTSD. Those type of providers have specific techniques to help you get thru all your pain. It may take time and it may be the hard, but if you want to have a normal life then this is the road that you should drive down.
Reading your post made me remember how all that was, gosh it ran my freaking life, it was getting to the point that I couldn't drive in traffic on the highway, I was so afraid all the time, worried, and anxiety, I had so much anxiety that I called it nervousness, because I didn't know what anxiety was, I used drugs and liquor to help me cope, those being self prescribed drugs
Now how to find a provider, I have heard from other posters that the VA is the not best place to go, so you work, do you have health insurance? If yes, then ask your dr if he/she knows of any PTSD therapists, or go to google and do a search like using the name of your state and PTSD providers or the name of your city and PTSD providers. Or use the Phone book and once you find a provider, call them and ask questions, how long have they been doing this? do they know the techniques to use to help you, and if you start with someone and you are uncomfortable then move on, don't feel obligated, it is your $ and your time. These providers they are out there, a psych or regular therapist doesn't have the tools that are needed to help you get the pain out and put it away, where you are in control and not the PTSD.
I hope you check this board again, I hope you find someone to get you back to you, you pre Afghanistan