Grr, it takes time. Like everything else, to be able to detach not only means that you know about it or understand it, but you've got to practice, practice, practice. Whenever I react to what my H does, I think of it as riding in his coaster, and classify that as backsliding.
Can't help it though. Our brain works as long as we are awake, and doesn't stop analyzing. But we can control it - think of that big red STOP sign MWD teaches as a tactic in the DR book. Or get a standard scenario to think about when you are feeling that downward spiral coming on. For me, I try to imagine that I have won the lottery and what will I spend the money on. That surely lifts me out of my funk.
Funny thing today though, while waiting for H to contact me as he just flew in from a 2 week business trip - his plane was late, and I was gettting worried, atthe same time wondering if the reason he wasn't calling me was because he was calling OW first, etc. etc, building up resentmemnt.... and suddenly I thought of what would happen if he was in a plane crash.... that sort of threw me off and made me laugh... and off course 5 mins later he called.
Me:49 H:45 D:12 M:14 T:18 Bomb: 6/26/10 EA: 9/3/10, fizzled out slowly, now ??? 11/5/11 Retrouvaille Finally piecing.... Its peaceful at last, but we got a looong way to go