Yes. Does she live at home? Does she go to school? If she is not going to school she should be contributing. Demand she pay rent or move out. At the same time withdraw from being her 'keeper'. She should be making her own meals, laundry, etc.My own daughter was a handful. After 3 months of paying for her room and board she quickly established some self sufficiency and moved out. As hard as it is you need to let her go and do this. In the meantime never back down. When setting your limits don't say anything you aren't prepared to carry out.

When it comes to her mental health, there is a fine line you need to find between being supportive and feeling held hostage by her threats. You may have to gather your wits about you and leave her to her own devices. Being there for her is different than running your own life according to her threats.