Tell her that somebody saw her near(not the village, but somewhere in between) when she was supposed to have had the flat tyre. Don’t let her know that you know the actual village. She won’t know who you know or who saw her. Mood swings, lies, gambling…. Do you seriously want to live your life with someone like that? ‘Bedroom action’ shouldn’t sway your decision.
If she cannot talk it out calmly; you’ll have to put up or get rid.
Problem is if she is cheating, she won’t admit it. Even if you went there… what would you expect to see? If you went just to gather evidence, everyone would know since you would be the only foreigners around for miles. The crux of the matter being that you need to be prepared to get rid if she wants to play hardball and not be honest. Otherwise, why bother to even check?