Throwing Up

Okay, so I guess I don't have the intestinal fortitude I thought I needed for this. Today, Rebecca stayed home for the morning to volunteer at the girl's school for swimming lessons. This kept her from work until I could drop her off around 2:00pm. I then went back to work and worked until I had to pick our daughter up at 3:30pm. About the time I was picking up our daughter, G had convinced my wife to have coffee with him. She agreed and they had coffee.
On the way home after work, she told me about the date. I told her on the way home this is why we need  the rules. She said her only rule is that nothing will happen. I told her she's already breaking her own rule by meeting him so regularly. She's in denial.
When I got home, I went for a run in the rain/snow. As soon as my run was done, Rebecca had to go out to a PTA meeting. We haven't had much time to talk. I need to talk. I saw that she was online today in the morning during our daughter's swimming. She wasn't talking to me. Upon that realization, I ran to the toilet and threw up. She didn't mention that.
I don't get it.  I've read about marriages that develop the HW relationship where the wife loves her husband and they share everything. That's what I believe we could have had. Where is our honesty? Should I let this emotional affair continue and pray that she comes back to me? Should I put a stop to it now and have her resent me? Is this where the old cliche of setting her free comes in? I think I need to go to the washroom again.