Have you considered finding and attending Al-anon meetings? They can help you learn detachment. You have taken the first step by admitting that coercing, cajoling and pleading do not work. It's much the same as with the alcoholic in that we won't truly detach until we are ready and have had enough. Telling her to leave is a good first step. Detachment doesn't mean you no longer care, it means that you are allowing her to make her own choices about her own life, and you are taking care of yourself.