Least said, soonest mended!
Your "friend's" testimony counts for nothing! The elders need two witnesses, and they're relying on you to admit what you said to her.
So to save giving grief to yourself, your husband & his family, insist on being told what the purpose of the meeting is about.
When they reveal it's concerning your private conversation with one person, thank them for their concern, but tell them that you would never discuss with anyone, things which may or may not have been said in a confidential conversation! Ask them why they didn't tell Sister Righteous to apply Matthew 5:23,24 & Matthew 18:15.
If they do not have two witnesses, they are dead in the water - and they know it. All the best.