re: Rock (wife) between (me) Hard place (my family)

I've been in a situation similar to that, except it was between me and my former mother-in-law. Just don't let it become a rift between you and your wife. It caused a major rift between myself and now my ex-wife, but I wouldn't change anything.

In short, my ex-mother-in-law was sleeping with everybody in the small town where they were living and my ex-sister-in-law caught her in the back of new neighborhood with another man. My ex-wife and ex-mother -in-law refused to tell my father-in-law and wanted to act like everything was fine, but I refused to take part in it. He eventually found out and they are now divorced but it definitely damaged my marriage.

You're in a tough spot, but make sure your wife feels supported by you because family squabbles came get out of control. Wish you the best of luck!