Paul, How will you know whether you should head home or crash at the office?
What has to happen either way for you to make a firm decision?
If your decision is that you are too mad to go home, then I would call W and tell her that. Why wait? You will just lose your nerve.
On the other hand, if you can't see yourself really going through with it then it's time to come up with Plan B.
Good luck and I know exactly what you mean about other people being able to see it more clearly than you can. For the longest time I let my H's obvious love for me cloud the raw facts that were right in front of me--namely, that he had emotionally checked out of our marriage long ago and his love was more companion based than anything else.
