I really hate to see you here! First things first. Try to relax just a bit. Get a grip on your emotions here for a few days or so. I know that is tough! But you must.
If he knew you would hear him when he said it, he is just a sh!!bag and was never your friend anyway. If he didn't know you were there, there still may be the chance that he is a sh!!bag and just acting the wishful wolf! Or, the intuition you are struggling with is true. I hope not!
I kind of get the feeling you are searching for evidence to one way or the other.
Take this with a grain of salt. If your wife were to be having an affair with him she may just have seen the true him. You need to plan A your !ss off and show her there is no other man for her in this world and she would be a fool to think anyone could compare to you!
Now, about the HR thing. It is called Ethics in the Workplace. Every company has one in place. Some frown upon this and some may not. An annonymous call to their HR department will let you know how they treat these things. This is indeed sexual harrasment in the workplace if your wife chooses to file. The company wether they like it or not are in this beacause they paid for the party. That makes it a company sponsored event.
Tread lightly for now. Do not give up your hand until you are holding 4 aces.
If you want to go to the info gathering stage email me and I can give you a few tips. I hope it does not come to that and you find out this is just a pig you thought was a friend.
stinkytheweez2003@yahoo.comYou could also tell your wife that if she were to tell HR you would not doubt her commitment and your trust for her would be intact. Only you know how to word it as to not LB (Love Bust)
Good luck my friend