I pondered for awhile before writing and deciding to post this, so......If you're squeemish, don't read the rest of this post. I make no apologies or disclaimers.
I am a suspicious and skeptical person, attributes that I consider to be qualities, and qualities that I attribute to so many years in my chosen profession. I write this based on the limited information you provided in your post:
If it were me, my suspcions would not be revealed while I interviewed my wife. I would begin that the next day by, in the gentlest of fashions, asking her to recount, in her own words, the previous evening's events. I would listen patiently with nothing more than encouraging words. I would gently ask any questions necessary to fill in any "gray areas". The more gray areas there were (taking into account any lingering effects of a drug, if there were one), the more inconspicuously suspicious I would be. This "statement" by her would quite possibly tell me more than I needed to know and would also suggest to me whether or not I needed to "question" more people.
My suspcions would also not be revealed when I interviewed AND interrogated as many persons as possible that attended the "party".
Being skeptical and suspicious, as I said, I might be afraid of what my investigation revealed. If we seek the truth we have to be ready to stomach it, depending of course on what the truth is.
I hope, if you choose to investigate this matter (and you should!!!), that it turns out there was a crime perpetrated by someone at the party and that you can prosecute them for it. Or......that it was innocent and harmless.
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DON'T BE SCARED
-Stretch