You should keep you vermouth shut, act very Cosmopolitan, and rum like the wind instead of letting your bad feelings ferment. Just whiskey yourself away for a while (maybe to Manhattan?) from that toxic situation. Maybe go someplace warm, watch a tequila sunrise and have sex on the beach with a girl named Margarita. Staying and wining or making a big brewhaha won't help. But be supportive and there is a martini tiny chance she will liquor problem eventually.