How can you be so sure aliens exist? Shouldn't you consider the other possibility as well? Every theory you'll name up indicating the presence of aliens has another potential explanation not having to do anything with aliens. What if science proves somehow aliens do not exist after all, which is a perfectly fine chance... You then have fully believed in a lie all that time, and if that '100% sure' of yours is not really 100%, then what else is flawed in your believes? I think such questions you should ask yourself prior of claiming you're a 100% sure of something.
Keep both feet on the ground, use your rational mind and you'll be fine.