How do I deal with this dog!?!?

I very, very seriously doubt that she is anywhere near "the worst dog ever". She very simply needs training. Take her to obedience cles where someone can teach you how to train this dog. You can hardly blame a dog, yell and scream and smack her, when she clearly has not been trained. She doesn't know she's doing anything wrong because she's never been taught the right way, but you feel free to punish her! Take her to cles before her temperament is permanently ruined!