Hi, there!
Beforehand, by no means I wish to sound harsh. Many others here can be of much more help than me, but I'd like to help you getting things into perspective in the hopes that this will help you organise in your mind what you can learn from everyone here. I just think I can relate to your situation.
First of all, you must know you're on your own when trying to help her. By this I mean that she is in no shape to provide support, understanding and probably most of the time you won't even feel her caring. Remember she's sick, and it's a hard process to get even a slight hold of this issue. HOWEVER, this doesn't mean she doesn't love you, her mind is just swarming with other, very intense and disturbing thoughts a good deal of her waking time. This being said: find your own support elsewhere. If you get emotional and that's not good for her, take it up until you get to vent with someone else.
Second. If you have already identified her triggers, best is to avoid them until she has had some counseling in dealing with them (and even then you must be careful); keep in mind that even with professional help it can take time. Again, she's sick, and avoiding her triggers is just like keeping away form bee-hives someone who is allergic to bee-stings.
Third. In the thick of an "episode", she's not herself. She's alert 24 hours a day, every single day. Her heart racing all of the time, with trouble sleeping and haunted by obsessive thoughts. Her mind is telling her that she's in serious danger and she must fight it off in any way possible. In short: if she hurts you in any way, remember it's not personal. Think of it this way: when your are in the middle of a flashback, you ARE in the middle of that memory. You don't hear, see, smell or feel the present. You are NOT REMEMBERING, you are RELIVING with your entire mind inmerse in it... probably the closest thing is a really lively dream. It is just like you were there all over: the sensations, the feelings, and the pain are fed up to your brain again, just like the first time. And she'll be there... over and over again... If she hurts you in any way, remember she's somewhere else, trying to protect herself, and she can't know she's hurting you. Again, talk about it with someone else, and it is best to not even expect an apology.
Fourth. Most of the work in dealing with this is done inside her head, everyday, and that's the kind of work that darins the soul out of anyone: a good deal of the time she is in no condition to think about your feelings and needs. Most people she knows don't want to see and hear her suffer by relating her traumas and pains... not everyone has it in them to sit through a PTSD sufferer's ventings. The thing is that most of us need to do it MANY, MANY TIMES AS A PART OF OUR COPING WITH THE ILLNESS. If you can take it, take it as many times as she needs it. She will not calm down, and she will be in dreadful shape all the way through every retelling of the events... but it will help her more than you think.
Fifth. And most important: you are there with her by your own will. It is your choice to be there, for whatever reason you find is driving you to do it. It can also be your choice to leave. There's no sweetening-up here: there are even forums for PTSD sufferer's spouses, so you can probably tell by that simple fact that this is real and harsh. If you decide to leave, no-one can judge you, for whatever reason. If you deicde to stay, take my admiration beforehand, and know that you will learn the meaning of unconditional support. Either way, you must be deadly honest with yourself in what your reasons are, and how strongly they move you.
Lastly. It gets better. With counseling, medication (as prescribed), and support from her loved ones, she will get better, even if it doesn't completely disappear. And I'm sure as hell it will be worth it for everyone around her. And I'm just as sure that she'll be thankful and willing to enjoy life even more than before her illness. Forums like this one exist because many, many people have come to learn that there's a way back from this horror, and that life afterwards is well worth it.
I can just advice you to talk to her about joining this site (or any other like this she finds welcoming), and finding professional help.
Good luck!