Eva you do everything and more for your children and I suspect sadly they have come to expect and dare I say rely on you to give your all and more. This I wonder, really wonder if this is what gives your youngest strength and ammunition to continue to rebel and deliver to you what she thinks is the ultimate "so there". Maybe you could join her, just hang out with her and behave as she does, don't make a big thing about it, just do it. Take a break from yourself, give your body and mind a holiday from your usual pattern of behaviours and thoughts. I don't mean abandon her or all that you have striven for, just let her experience a sliver of life without your parental input, you have little to lose my dear.