Hello, I'd like to help you with your question.
It sounds like you are experiencing complicated and traumatic grief and possible PTSD because of the way you found your son and the way he died. It does not sound like this was a natural death and anytime that occurs, you can experience an extreme response.
And it also sounds like there might have been anti terrorism involved, which just on it's own usually brings PTSD issues due to the heightened state someone needs to be in and the secretive nature of the work.
Flashbacks are like being in the actual situation. The trauma occurred to your whole body. You were involved physically, mentally and emotionally in trying to deal with what was happening to you and what you were seeing. That involves an enormous amount of energy. When you have the flashbacks, it is like being there all over again and using that energy again.
Flashbacks are your mind's way of replaying the trauma to help you cope with it. One way you can work on eliminating the flashbacks is to acknowledge and accept what happened. This is not easy, but letting yourself see that you could not control what happened and letting go can help.
Your mind keeps bringing the situation up and putting the incident in front of you to say "this needs your attention." By fully acknowledging it and exploring your feelings around it, you pay it the attention it needs and your mind can let go.
You may want to consider a journal about the flashbacks. It makes it easier to put what happens on paper so it seems more real and you can go back and work with what you wrote. It may also help you pick out details that you may forget about but are important to your recovery.
Therapy is a good option to help you learn to cope and provide an opportunity to have support through the grieving process. It may take longer because of the complications of the situation and therefore more severe symptoms. If you feel therapy is not helping at all, you may need to try another therapist. Sometimes it is just a matter of finding the right person to help you work through your feelings.
You also may want to use support groups and self help to intensify your recovery work. Learning more about the grief process and how PTSD can affect you can help you get a better understanding of your symptoms and how work through them better. And sharing your grief can make you heal faster. Here are some resources to help:http://www.helpguide.org/mental/grief_loss.htm http://psychcentral.com/lib/2006/the-5-stages-of-loss-and-grief/ http://www.ptsd.va.gov/ http://www.helpguide.org/mental/post_traumatic_stress_disorder_symptoms_treatment.htm
Getting Back to Life When Grief Won't Heal by Phyllis Kosminsky
The PTSD Workbook: Simple, Effective Techniques for Overcoming Traumatic Stress
Symptoms by Mary Beth Williams and Soili Poijula
I hope this has helped you,