Are you sure she is an alcoholic or is she someone who abuses alcohol and acts stupid when drunk? Though blackouts are a sign of potential alcoholism, I'm not sure they are solid proof. Nor is excessive drinking or inappropriate behavior when drinking heavily.
I ask this because if she is not alcoholic--if she does not have the disease of addiction--then your communication with her, using "I" statements, could eventually have a positive outcome once the air is cleared.
But if she is alcoholic, then the relationship you will be attempting to negotiate will be your relationship with her addiction, and there is very little hope of working things out. She has to be clean and sober, and for a while.