@windswept , I don't know this guy, or his background, other that that he's a combat vet & he has PTSD. Some combat vets with PTSD had the PTSD BEFORE they went in to combat, from other things. Don't know if this is true of this guy or not, but it's something to consider.
At least some of my own "trauma" involves sex. By now, I know myself and my reactions well enough to know that there are a couple of things related to sexual situations that I have some problems with. (And I'm dramatically minimizing when I put it that way.) At some point in a relationship, if it looks like sex is going to come up, I've decided that I need to mention this to a potential partner. Generally, what I say is, "If you do 'this' stuff is going to happen and it won't be good." If that's a deal breaker, fine. It's a good way to sort the wheat from the chafe. But, SOMETIMES, they don't take it seriously enough. Sometimes they don't get it, or are so into what THEY want that they lose track, or what ever. In that situation, I can absolutely guarantee that I'm going to be triggered to the extent that something bad might happen but it probably won't be happening to me. And, I know, by now, that what I'm seeing/hearing/ experiencing in the moment won't be the same version of reality as anyone else in the room. This is REALITY. It just IS. Does that make me a jerk, if I blow up at someone in that situation? Or try to hurt them? Because in my version of reality, in that moment, it's going to be life or death, him or me, and it just IS. If it does, so be it.
I don't know that what happened in your situation was a flashback, but it sure sounds like it. From my perspective there was no part of that that was him "treating you" in any particular way. He was reacting to the situation as he perceived it, from the sound of it. That doesn't make what happened YOUR fault either. Had you mentioned in your original post, that he told you to leave, you leaving wouldn't have struck me as a questionable idea. You didn't. So, I made the assumption that you just walked out on him. My first choice would have been for the person in your position to realize what was probably going on (since you knew he had PTSD and have a good understanding of what that involves) and then for that person to quietly and calmly try to assure the person having the flashback that things were ok, everyone was safe, what ever it was they thought was going on wasn't what was going on, etc. (Assuming all of that to be true,) Just walking out on him seemed rather heartless, but, if he told you to leave, then leaving was the right thing to do.
When you gave the condensed version of the story, you condensed out some pertinent info, I guess.