Awkward situation

[Coconut]

Tate,

You are in a terrible predicament and I feel for you, I can't even imagine the struggle you are going through knowing what you know and having your sisters life so intractly intertwined.

I am going to come out and say what I think, because I think you may be looking for someone to shoot straight from the hip.

You SHOULD NOT allow your wife to vacation at your sisters house.

If you want to handle it as softly as possible, I would suggest telling your WW that she needs to cancel that trip, if she doesn't, call your bill and tell him he needs to cancel that trip, if neither of those options work, you need to call your sister and fill her in.

If you have any kind of good R with your sister, allowing your W to go there knowing what you know will ruin that, and no matter what, she will be your sister for life. Go down the line, set your boundaries, make sure your WW and your BIL know you will tell your sister if they don't cancel the trip, but DO NOT allow your wife to go on that trip without your sister knowing everything. I don't think you'll be able to forgive yourself, or your sister will ever forgive you, if it goes any other way.

I would put my sister before my W every time in your scenario.