Others have provided great info and opinions. I read the "Opening a Monoship" that GalaGirl provided (because it was one I hadn't seen before) and think that it would be useful to have your wife read.
I realize that her potential "other" is two states away, but meeting for sex at this point seems to be really, really rushing things. I think a shorter, non-sexual meeting might be more in line while you are struggling. Could they meet somewhere public 1/2 way between for a day together? Could you and she travel together and then have the three of you meet and then you go off an do some other activity for a few hours?
You might want to check out Phy's blog on this site where she talks about going to spend a weekend with her OSO for the first time...it might give you some ideas and talking points.
Me: poly bi female, in an "open-but-not-looking" V-plus with -
MrS: hetero polyflexible male, live-in husband (24+ yrs)
Dude: hetero poly male, live-in boyfriend (5+ yrs) and MrS's BFF
SLeW: platonic girlfriend and BFF
Lotus: "it's complicated"
+ "others" = FBs, FWBs, lover-friends, platonic G/BFs, boytoys, etc.
My poly blogs here:
The Journey of JaneQSmythe
The Notebook of JaneQSmythe