Hi, I really hope you're not going through this natural and understandable process on you own. You may actually have PTSD; it doesn't just happen to people who have been in the military.
You are trying to be strong, but no-one is fearless, or if they are they're probably not normal. Don't be too hard on yourself.
Can you afford or find a counsellor to help you process these memories? It really helps to talk to someone. I've been through a situation that traumatised me and found counselling speeded up the process of recovery.