drainbamage
Keep HBT weird.
I am going to play Devil's Advocate here. If the marriage is otherwise in good shape and you don't have firm evidence, I would be open to a convincing explanation. I could imagine in a corporate environment sexual harassment is often accepted. She could be under pressure to put up with lewd advances and such to keep her job. Could that be what is going on here? From what I can see, the incriminating texts are more on "Steve"'s side than hers. This does not seem to be about her trying to sabotage the marriage, otherwise your talk would have been her opportunity to end it.
I don't know, if the guy is sending her overtly sexual texts, there's a big difference between "I'm just going to put up with it to keep my job" (which she shouldn't have to do under any circumstances) and responding/playing along/encouraging the behavior.