So you had a great weekend, marred only by what your son overheard the neighbors wife talking about with your wife.
You did great at not bringing up relationship talk and just going with the flow. I agree with Phoenix that you should be cautious about assuming that her behavior this weekend means that things between you are thawing. Continue to be detached (and yes, I think you're definitely getting it) and life your life as if everything will be fine.
Hopefully the therapist will continue to help. But that really is a matter between your wife and the therapist. Nothing you can do about it either way.
I can't figure what the best approach is with the neighbors. It does appear as though there is no longer any "romantic" issue between the H and your wife, but there is definitely a harmful influence. I would agree that your wife sees their life as much more carefree than hers and probably desires that.
As Phoenix said, be careful about committing to very much financially in terms of this new venture your wife has expressed an interest in. In starting ANY business, there should be a huge amount of research done before ever beginning operation anyway, so steer her in that direction before considering finances. You definitely need some time to see how this situation continues to unfold.
Sounds like you did well. Stay strong.
Bill
"Don't tell me the sky is the limit when there are footprints on the moon."