This is your wife, it's not on! There's websites devoted to confronting such behaviour on dating sites, and it's not uncommon unfortunately.
Tempting as it might be to get out there and confront the situation, the advice others have given about "is it safe to" must be considered.

Really though in a relationship, the biggest thing is trust - once this goes, the relationship at best is never the same again, and at worst is finished. There must be a severe dent to this trust to be posting it on a public forum

Oh by the way, you said her visa was granted in August, but in a previous post you said it was granted in October?