I really liked the input you got from BLT (
BLT!) but wanted to add to it. 
What you are experiencing is the difference between your implicit and explicit learning. (For a lengthier discussion of implicit versus explicit learning, see Learning Developmental Skills Part 1 on my blog.)If all we needed was to change our explicit, cognitive understanding, then we'd all be able to just read a book and once we understood, as you can understand the danger isn't real now, we'd all be cured (wouldn't that be a nice system? I know I'd vote for it.
) But the part of our brain that is tasked with keeping us safe, the amygdala, is not all that sophisticated. As my T is fond of saying, we have the same amygdala a hamster does. The amygdala is pretty primitive and basically asks three things when it encounters something: Do I eat it? To I flee from it? Or do I make love to it? Not a lot of nuance. It is also biased towards responding strongly to fear/danger. Think about it. If you're scared when you don't need to be, no harm done except for some increased stress (it wants you safe, doesn't care about happy) but fail to be afraid when you need to be and you can end up dead.So we have a long line of ancestors that passed on a high reactivity level to danger. The amygdala learns implicitly, so one of the things that happen when you experience trauma, especially long term childhood trauma, is that the amygdala forms impressions of what is dangerous by tracking what is going on when you get hurt and then telling you to avoid that. In long term trauma, these are lessons learned on a VERY deep level that are reinforced over and over.
Fast forward to adulthood, where normal relationships will place you in a situation that "feels" dangerous (because you were wounded and hurt in relationship) and your amygdala senses danger. Our brains are built such that the connections FROM the amygdala to the frontal cortex are wide and strong. So when the amydala is screaming to get out of dodge, we don't stop to question it. We get out. When your fear is strong enough, your frontal cortex is actually flooded with hormones that interfere with your cognitive ability so that you will act and not waste time thinking. You're not imagining that it literally gets harder to think when you're scared.
The connections back from the frontal cortex to the amygdala are relatively few and weak, which is why to retrain our amygdala we need to be in the presence of an attunted regulator. That way when we get triggered and our emotions shoot off the scale, they can calm and regulate our emotions enough to allow the frontal cortex to get a word in.
So while you can immediately understand in a cognitive sense that you are no longer in danger, your amygdala has to experience the "dangerous" situation time and again with a DIFFERENT outcome than you experienced during the trauma, until it "learns" that there is no danger.
It's a very different process and one that is magnitudes easier as a child when the rate of change in your brain is much higher. And it's frustrating to not have your feelings follow your understanding. The problem is that feelings follow actions, not understanding. So you have to keep experiencing the triggers but having it turn out differently, over and over, until you can offset those early lessons with more recent experience.
It sucks to have to do it this way, but on the upside, thank heaven it's possible. It may be painful, slow, confusing and frustrating but at least it can be done. So you're not being stubborn or weak or stupid or slow (just grabbing some adjectives from my own inner critic tapes
) by not being able to stop these feelings; you're busy rebuilding your brain structure, which is hard, slow work. AG