I'm in a slightly weird position, because I know exactly how it feels to go through everything that you're all describing, and more, as the wife of a former soldier who has combat PTSD, but I also know (as well as anybody can, since we're all different), what goes on in the head of a PTSD sufferer, because I have it too, although mine is from childhood.
My hub and I were already living together when he started to show really bad symptoms, so he couldn't just cut me off completely in the way that he could have if we'd lived separately, but there were times when his body was in the bed next to me, but HE was nowhere in sight. He locked me out... he tried to hurt me (both consciously and not, physically and not)... there have been months on end where he was just a different person. He once accused me of 'constantly pawing' him for trying to give him a hug.
It's taken a long time, I've made massive mistakes along the way (pressing when I shouldn't, questioning when I shouldn't, etc), but he's worked really, really hard to get better, and he's doing really well now. He's just had a bit of a blip due to redundancy, and we still get the regular 'something good's happened so now things are going to go boom' attitude, but it's so much better than it was. I also still get the 'you never signed up for this', the 'you'd be better off if I were dead', the 'I don't deserve you', the 'go on then, leave, that's what you want to do anyway'.... but not as often.
We've now been together for 18 years (as of next month), and we're not in any immediate danger of splitting up, so things can work. It's really not easy, but then what is?
The trouble is, since I'm now becoming more self aware, I'm realising that I do a lot of what he does. My spells of being cold and distant aren't as long or sustained as his, but they're just as cut-off. they usually happen either when I can't cope with my own emotions, so I subconsciously shut them off (even the good ones), or when I feel like I'm not good enough, or not deserving of him - when I feel like I'm being a burden, and he really would be better off without me, so I'm half-heartedly trying to make that happen without actually making it happen (if you see what I mean). Also when something he does triggers me (whether I know it has or not), and I'm actually reacting not to what he's said or done, but to something that happened 30 years ago.
Anyway, in short, I know exactly how you feel, because I've been there, more times than I can remember, but if you can find a way to hang on, and to deal with it, then there is light at the end, things can get better, but only if you both work at it. I found learning to try not to take things personally worked for me. And to talk through things after they'd calmed down, and explain how it makes you feel, even if that wasn't his intention. and giving space - encouraging his interests if he's well enough to have them. encouraging him to spend time with friends without you, if he can.
Making it clear at the same time that you don't know how he feels, because you're not going through the same thing, but that you know it's bad, and not entirely about you. (That last bit now strikes me as fairly heavily ironic in my situation, because I've apparently had PTSD longer than he has, so I really did know!)
Sorry, rambling now so stopping.