If you were my friend and you found out my husband was cheating on me, I'd expect you to tell me. In fact, if you kept it from me, I'd conclude that you were 1) not really such a good friend after all and 2) possibly also sleeping with my husband.
What she does with the information is her business. What YOU should do with the information is give it to her. Tell her exactly what the woman at the party said. Word for word. Be sure to have some chardonnay on hand.
