If I was presented with undeniable proof that we did indeed make peaceful contact with aliens (or the other way around), I'd say,"Oh, OK." and go back to what I was doing. If it was hostile, I'd say,"Huh, that sucks." Either way, it doesn't matter what I do. Might as well not let it affect me for as long as possible while any problems are worked out. If the aliens come for me, I'd probably just go with them. Or fight them if they mean to kill me.