The bigger question - will you feel worse if they find out about it on their own? One thing I learned growing up is that no matter how sneaky you think you are, your parents somehow usually find out about it. And sometimes it was the things they never admitted knowing I did, or suspected, that made me feel the guiltiest & worry most. Even to this day, grown up. Occasionally it's best to come clean & admit what you've done wrong to have a clear conscience. Even if you're pretty sure they will probably never find out about it.