how do i deal with the changes in mood?

my wife is diagnosed bipolar. it shows. one minute she is fine the next she is telling me to go the F*ck away, one minute she is telling me she loves me and could never live without me, the next she is yelling at the top of her lungs I'm leaving i dodon'tare about you I'm going and I'm never coming back. these very opposite emotions are scary and sometimes really hard to handle. how do i make it thru and not lose my confidence in myself. i really love my wife. i know the person she can be when shes kind but the person she is when she is mean terrifies me. how do i deal. what can i do or say to make the episodes less extreme?