Why do you keep convincing yourself that nobody is going to find out?

Seriously, I don't know what it is but I can see that you're desperately trying to hide it. Perhaps you want to confess to it somehow, but don't have the strength or the courage to do it. Is it really that bad? Is it something terrible, oh my goodness, it is isn't it? How long do you think you can keep up this act, before someone suspects something?