You realize you have feelings for Kim on par with those you have for your wife. You talk about it with Kim, but NOT your wife. You are shutting her out and forming a bubble of free discourse with Kim. You are surprised your wife is feeling more need of reassurance?
You say your wife and Kim are also friends. You go to Vegas with Kim. Your wife tries to spend more time with you and you and Kim see it as she ruined something for you two. Did you inform your wife of your plans for that day or is this another thing you did not share with her and can now conveniently hold against your wife for unwittingly ruining?
It might be a good idea to step back and count the blessings shared with your wife in the last 10 years and recognize that if she were not who she is - you wouldn't probably wouldn't even know Kim to have these feelings for in the first place. Your marriage to your wife is the vehicle by which you were able to express yourself sexually with this woman. Maybe go thank your wife and give her a kiss.