I'm going preface this with an fyi that I'm a woman and have been sexually abused.
OP, there is nothing wrong with you being suspicious. Your wife has proven herself to be unreliable, and you simply don't know what happened that night or in the time period leading up to it.
She might be telling the truth about being sexually assaulted, or she might be lying. Yes, both are completely possible. That "believe all women" mantra needs to be changed to "take all women seriously". Her claims are serious and indicate assault if they're honest, however, your wife has a track record of dishonesty and a strong motive to conceal the truth in this case.
Two things could have happened:
1. Your wife repeatedly romantically/sexually chatted with this guy in violation of your marriage vows & harming your relationship, then lied when you questioned her about the texts, claiming she "can't remember" basic details about the texts such as were there a few or a hundred, which is impossible and a classic cheater dodge. She failed to take responsibility in therapy and tried to push the blame on you. And aside from that, she was sexually assaulted by the guy she'd been romantically/sexually chatting with.
2. Your wife did all of the above, but instead of the sex being an assault as she claimed, it was actually consensual, and she panicked the morning after, realizing it wasn't worth it, people might talk, you might find out and this might end her marriage. So she filed a complaint against the guy at work (noticeably, not with the police) to cover her tracks, suspecting that the complaint wouldn't go anywhere due to lack of evidence, but not really caring that he might lose his job, anyway.
Those who think Option 2 is impossible are being naive. A person willing to betray her husband by chatting romantically/sexually with a known womanizer, risking her marriage & therefore the well-being of her children for an ego boost, and then deleting most of the texts and lying to her husband about the extent of her involvement, can certainly be capable of lying about another man at work & risking him getting fired, in order to cover her tracks to protect her marriage, reputation & financial stability.
The only way you can get close to the truth, whichever it is, is to insist she take a polygraph. Without that, you'll never be able to trust her again & the marriage might not survive.
She can handle being asked about that night, even if she was drugged and raped. It won't be pleasant but she can report what happened to the polygrapher, just like she reported what happened to you and to her boss. Just like you were traumatized by her infidelity, but can talk about it with her and during counseling. It's stressful but you're both adults and can take it because it's important to your marriage.
If she claims she just can't handle a single polygraph, it's a dodge. You should give her an ultimatum on that because it's the only way to have reasonable certainty about what really happened.
[This message edited by morningglory at 4:20 AM, Saturday, May 7th]