I don't see this as her having two separate incidents with this guy. It was a continuous relationship and it never stopped. They worked in the same place and didn't have to text each other, but they still did. The day in the bar when you had a beer with this guy and he and your wife texted while you were there was a sign that something was terribly wrong. His reaction to your confronting him was a good indication that this wasn't ending.
He may have initiated contact, but she never backe him off it one bit and she actually pursued it. Even if you never expressed an ounce of jealousy towards this guy, she intended to have an affair with this guy. Now, you're jealous nature in general, over an extended period of time, that may have made you very weak and unattractive to your wife.
Your wife's pay is based more on her ability to flirt with men than it actually is based on her ability to serve them drinks. YOUR WIFE'S JOB IS TO FLIRT WITH MEN. This is a recipe for disaster in your marriage.
Some men are unreasonably jealous. Their wife goes out to get the mail, a car passes by, and they accuse their wife of flirting with the driver - that's unreasonable. You are jealous, but you have a pretty good reason, which is that your wife's job is to flirt with other men, how well she does it determines how much money she makes, and some of those guys are wealthy, young, good-looking, funny, etc. She is bound to find some of them attractive. The problem is, your jealousy does make you unattractive.
However, no one cheats because they were accused of it, saying we might as well do it if we're going to be accused anyway. She cheated because she liked this guy and wanted to cheat, she just used your accusation as a justification after the fact.