Oh mah god! I'd like to say I'd destroy all evidence of it, but I'd probably use if first and then get caught somewhere like the last ice age. Oh well. That's what I get for not destroying it in the first place.
If such a secret existed it must always be destroyed, otherwise we would be overrun by travellers from the future, and continually seeing sudden changes in our history books.
i think i would use it as long as i could safely travel back without becoming messed up or anything. then tell someone i am close to about it. definatly not show the governement or scientists though