What do you mean, you've been hearing it wrong? Unless you're studying Classical Latin, the anglicized pronunciation, which is based on the Vulgar Latin one, is the "right" one. Same with other Latin names and words. In Classical Latin, Cæsar was pronounced much like the modern German Kaiser, which is based on the Classical form and preserves its pronunciation (though it modifies it to fit German spelling), and when he came, saw, and conquered, he pronounced it like "Weni, widi, wiki."