Good post Sean. I understand your situation. Even though all systems are go, there is something holding you back.
My suggestion is to go to a bar, have her sit alone where you can observe from a distance. Analyze your feelings as she is approached. How does it affect you to see her smiling into another man's eyes? If all you feel is pride and a tightening in your belt, you are probably ready. If you are uncomfortable in any way, you are not ready. As ready as you feel, these feelings are a warning, best to heed imo.
We were kinda in your situation and I bailed on opportunities for some reason. Then we had an event that could have ripped our marriage apart and she stuck it out with me. That gesture showed me her true colors. Up to that point, I assumed she would be leaving me at any time now. I didn't realize that she really does love me, which is what I needed to be able to accept her doing this.
We were tested when a male lover fell in love with J and felt she should leave me. He is really rich, really good looking, huge dick backed up with years of talent. Overall, a much better match for J than me. I barely flinched when she told me this. I was mostly bummed because we wouldn't be seeing him any more, he was a lot of fun lol.
Last piece of advise, looking for a bi man. Be ready to meet guys that are all bisexual until the time comes and you can barely pull him off your wife. Look through the posts here on how to find a reliable bisexual man, it only sounds easy.
Good luck!