I lied about my age on a Facebook group?

[Josh]

I joined a group on Facebook a few months ago and I like it a lot. I've made lots of new friends there. The problem is, one of the rules of joining the group is to be 18+ (it's not a porn group or anything lol) but I'm really only 17. I figured it doesn't really matter so I joined and got accepted because my age singly listed on my profile. As I said I've become really great friends with most of the people in the group, and I thought I was in the clear. But I'm worried what will happen when I really do turn 18 in a few months. I'm sure my family and friends will say something about me becoming a legal adult on my wall, the typical "Happy 18th!" type posts. But if this happens, I know a bunch of my new friends from the group will see it and figure out I've been lying to them all along. Please help, I'm not sure what to do.