Starsky309: Your reply I think hits the nail on the head in almost all aspects. You are confirming a lot of what I already very strongly suspect, that there is another man. I have a lot of forgiveness in my heart and won't say "never" to reconciliation even if things have crossed the physical boundary as well as the emotional one, even though I have been faithful myself I do consider it possible for her to come back and be forgiven if my conditions, still being formulated, are met.
Then if that's the case, my advice to you would be to proceed as if she is, and plan and act accordingly. There's little harm in that, while there could be a TON of strategic and tactical mistakes (not to mention, your HEARTBREAK) if it's the other way around.
False positives are always easier to deal with than false negatives.