Mike, I usually read your posts and I have to say that I admire your strength and the will to fight. You're a very brave person! ANd motivating for others, so keep up the good job.
About that negative thought - in addition to my panic/agora I also have OCD so I know a bit about the unpleasantness of recurring thoughs which are extremely tiring, etc, etc. What I do is go ahead with the thought during my two worry times a day. When some obsession is hard to deal with I spent ten minutes just talking about all that is associated with that thought - images, how it makes me feel, etc. As I said, I do it twice -in the morning, after I wake up, and in the evening. And in a few weeks (unfortunately, that's quite long...:)) the thought just goes away or loses its strength. That's how I have overcome my traumatic memories of my mum's suicide attempt.
Maybe this could be of any help?
Iwona