I told you this would happen in your last thread. You didn't react appropriately because you were afraid of something you weren't even sure would happen. And now look, you are even more afraid of wetting the bed, hopping a baby diaper will work for overnight. Too bad for you because no they will not work.
You've all but guaranteed your sister will find out now. Worst yet, she will probably be mad when she wakes up in a wet bed next to you. So ask yourself, is the fear you have now more bearable than they fear you had before. Because that's what you set yourself up for, and I told you it would happen.
Well, there is a bright side to all this. You are now forced to face that fear. And there's no better way to overcome a fear than by facing it. You'll be better off and smarter about needing diapers after you get past your camping trip.