I think I would tell them what you are doing. If you lie, then it is possible they may call you next week for a drink. If you are honest, you won't have to deal with this again, and if she is a good friend she will support you.
I've learned from my husband who is a crack addict the phrase "wet faces, wet places" is very true. If you associate with people who use early in your recovery it is a lot harder. He had to detach from his friends, some of whom he has known since kindergarten and meet new friends, mostly in NA, until he is strong enough to see his old buddies again. He says it was hard at first, but he can't believe what wonderful supportive people he has met, and they are all in the exact same boat, so the temptation of drugs or alcohol popping up is very minimal.
I would be honest. NA is an honest program.
Good luck!
God Bless.