@Puppy, I'm sure there will be, but I won't be one of them. Alas, I suffer from long torso/short leg proportions. But I'm happy to go see a traditional Vegas show!
@Burt, I understand, we've all been young and made foolish mistakes. I think if that's the only thing you'd lied to her about in all these years then she's the one who needs to let it go. And you probably could mention that the next time she brings it up. "W, I have apologized for that many times. I understand that I broke your trust. I have been honest with you since then. When you continue to bring this up it makes me feel ____. It's not productive to live in the past so let's figure out a way to put this to rest for once and for all."
As for not treating her like a child, I think following the Golden Rule would serve you well here. Stop and think about how you would react if she treated you that way. If you wouldn't like it, don't do it to her. I know it will take some practice but I also know you can do it.
If you love somebody, set them free. http://tinyurl.com/2empx2g