Hi Iam,
All of us PTSD sufferers seem to have exactly this same reaction at some point in the therapy when our resistance is rising to the things that therapy is dragging out into the open. Believe me, there isn't one of us that wants to go through these memories. The one thing that I've heard consistently from Trauma survivors is that they want to feel better but they don't want to know those memories. At the point where we are really beginning to see progress, our internal defense mechanisms are triggered to do anything to prevent the exposure of the pain.
It sounds like you've been working on this a while, but let it go dormant for a decade. Likely you needed to get yourself to a safe, stable point in life before you could open up this pain again. Now it sounds like you are in a supportive spot in life, so you are opening the box.
With therapy, you'll begin to see a lessening and fading of the symptoms. They flare back when you fight hard against exposing the memories. They DO fade when they are exposed. How long it will affect you depends on how strong the fight is in you. Medication helps. A good human support structure is invaluable.
The physical changes in brain structure may always be with us. That makes us prone to startle more or have a shorter temper. However, the flashbacks and other symptoms can fade once they are out in the open. And quite frankly, the startle/short temper is nothing compared to the flashbacks and other dissociative symptoms.
Before giving into total despair, remember that there are good things in your life too. Don't let the trauma fool you into believing that there's nothing but the bad. That's a part of your internal defense mechanisms telling you that it will never get better.
I was in therapy 13 years ago for about 2 years of intensive work. I had a decade where I was mostly symptom free until something triggered me at work. Now I'm in therapy again and I'm reaching a point in my own therapy where I'm going to find it difficult to handle for a while --bringing up damage that was never dealt with before now. However, I have the knowledge that there was a point after the last round of therapy where I felt great for years. That is sustaining me.
Don't let the trauma talk you into a corner. And there isn't a "time served" function of PTSD where a time clock appears to guide you through the therapy. ("If it's year 2, then I should be feeling this....") Everyone is different and some symptoms can resolve quickly. The main factor is you. Are you ready to face these memories down? The harder you fight to keep them hidden, the longer this takes. Once they are out in the open, the memories lose much of their power to hurt.