Do they not have phones? Where is the photo anyone would have taken to prove such a claim? Why not confront you there and then? This reeks of bullshit. Hopefully someone can confirm your presence at work. Did you send any work emails at that time? It would be hard for your wife to imagine her parents would lie to her, but hopefully if you can show you didn't do anything wrong this time, you'll be the one she believes next time.

I smell marriage sabotagers

Saboteurs

* saboteurs

Maybe you work at the bar?

He walked out in the middle of his shift with another woman then?

OP I made an account just to say this, get some evidence from your boss or just ask the boss to have a word with your wife, that you stayed in your workplace at that time.
Marriage sabotage is the most likely explanation to your situation, or a case of mistaken identity. (Of course she'll trust her parents more than you, but it doesn't mean her parents are trustworthy).

Any way you can get a time stub from work? At our work we can see what time we clock in and clock out. Everywhere is different, but maybe your boss can make it possible.

Seinfeld Episode........EXACTLY

Cant your boss say you were at work?

I sense not an evil twin, but evil parents-in-laws trying to sabotage your marriage... That really stings, I hope you get things worked out, OP :(

Fuckers...

Hopefully you can prove your alibi. Is there a reason to believe they would lie about you like that? Have you done something to make them want to get you into trouble with your wife? Is there a history of them not liking you? Common sense should tell your wife that you wouldn't leave with another woman right in front of your in-laws anyway. Is it possible that they are all in it together and your wife just wants a reason to get a divorce? So many questions. Hope there is a follow up.