I know I'm replying rather late to your post, but I watched a recent episode of Poldark where the character that plays a doctor seems to suffer from PTSD after his rescue from a French prison. Before I go on, I'm not a huge fan of the series, and as the scene began I was thinking to myself, "Oh, how badly with this suck?"
I was pleasantly surprised. The way he expresses his feelings gave me the impression that whoever wrote the script knew what they were doing. His life turned idyllic in seconds, something that here in reality might take many years, if ever. His character thereafter is unrealistically well-adjusted.
I'm working on some fiction too, which I've never done before and don't really have the slightest idea what I'm doing. My story too has a veteran only his PTSD developed before he ever went to war. He was sexually abused as a child and it was an experience in war that brought it all back to him.
I can relate myself to the sexual abuse at a young age. My story isn't a romance, though there's a romantic subplot. In short, I can put myself into him and and his feelings are actually mine. Otherwise, I made it all up. It is fiction after all.
You might want to check out this forum's sister site, MyCombatPTSD. You might find more relevant posts, first hand accounts, etc. that might help you develop your character.
I wish you the best of luck with your work.