Given I've only read a small bit about you, I can't say that my guess is anywhere accurate.
You are paralyzed by intimacy and trust.
As you work through this with your H, if you can understand that your 'enemy' is NOT him, but your incredibly honed defense mechanisms, you will understand that you are battling yourself, not him.
Tell him what you are feeling, explain to him what you are battling; talk yourself through your anxiety attacks and overwhelming urges to withdraw. Remember, YOU are the captain of your ship, not your emotions. The defense mechanisms at one time served a very valuable purpose --- your emotional survival. You are through the trauma, but your defense mechanisms don't know that.
You can be AWARE of your feelings of anxiety, panic, etc., and mentally step AROUND them. You do not have to give in to them, but you need to go slowly so they will not shut you down all together.
If you do shut down, don't worry about it. But you really need to tell your H what is up so that if it becomes too much for you, then he doesn't take it personally.
Remove yourself from him without lashing out at him, go into a dark room, collect yourself, and find your center. Then try again.
