Akrasia,
This:
My whole body seizes up ... I live in constant fear of a relapse. I was terrified ... I was terrified ... I literally seize up with fright
Does not sound to me like a nice way to live my life.
I have been in the exact same situation. This sounds like a boundary issue to me. My XA&ABF (who had done some really $hitty things in the relationship) was always talking to me about what he was going to do, drink, don't drink, whatever. When he would "share" with me his thoughts about what he was going to do I would panic, my heart would start racing, my mind would start racing, I would literally be shaking. But soon I discovered that his recovery is none of my business and I wanted nothing to do with it. My advice is investigate your feelings, determine what you want, identify your limit, and formulate your plan of action if and when the boundary is crossed. Then, communicate to him your boundary and the consequences for what will occur if he crosses that boundary. Then follow through with what you said you would do.
There are some stickies on boundary-setting on this forum. You can also Google it. The long and short of it goes like this:
John, when you _____ (fill in the blank), I feel _____.
Therefore, I would like for you to ______.
If you _____ again, I will _____.
About this:
As I've said in my other posts I got myself an apartment during his last bender. The only reason I cancelled it was because I heard him say, "I want to stop drinking forever," and he started medication and counselling. So I stayed because I thought, "Okay, now this is when we move on to happy times together. This is when it ends."
Makes me think of a ping-pong game. And YOU are the ping-pong ball. Not sure how much peace and serenity you get living your life this way but you may want to consider taking some steps toward stopping being the ping-pong ball. Just take baby steps because it is apparent you are not sure yet what you want to do about the relationship as a whole.