My SD turned 18 a few days ago. She collected some expensive gifts from her dad and a necklace from me to go with her grad dress. All seemed well until she dumped on her dad that night that she was living with her mom at the start of the summer. The younger SD of course will be bullied by her older sister to choose. Because her BM and the DH don't co parent the SD's have always decided everything in the family which has caused a lot of stress in my life. 
however last night something spectacular happened my DH finally saw his oldest SD act out fully what I think is a personality problem. The SD came out of her room and hid by the wall looking sheepishly at her dad waiting for his attention as he continued to talk to me about his day. Then she said I am not a stick person  and I know that you judge my body to her dad. DH then asked what have I done or said that makes you think that. I see how you both (me) look at me. Then she promptly looked at me and said I know you judge me. I said give me an example of how I have put your body down. I just know these are my feelings! My counsellor said you would do this that you would say you don't judge me but she also said that she was 90 percent sure that you are. You looked at me tonight when I took extra potatoes! I just shook my head and said please don't tell me what I am thinking and feelings are one word not thoughts. You can think what you want but don't tell me what I am thinking. She then turned on the water works and ran to her room so I said no you don't get to accuse me of something and then run to your room so she came back and her dad said give us examples. She then said you said surgar is like cocaine. I laughed and said yes that was a joke I told you when you were a child any recent examples? She then turned on the water works again and ran to her room. I stood outside her door and said I have never put down your body. Please don't accuse me of things I have never done. I then called her counsellor and left a message. Over this past year I have disengaged very well setting boundaries and staying calm but I am at the end of this crap now. I left a message for the counsellor who over the past several years even after reaching out to her last year has never spoke to us about the SD when she was a minor or kept the DH informed about her MH. I think she is really terrible at her job and has encouraged my SD how to triangulate which has made thinks really hard for us. While I am aware that the DH and BM should be calling this counsellor out and staying in more contact indraw the line when I am being vilified! This has been the pattern for years. My SD makes me the villain so she can maintain henr mothers love because the BM hates me and her ex! Tonight I very calmly said to my DH I am done. It's been six years of hell with her. She said she is leaving in July. Here's a thought why don't you tell her if we are such terrible people then there is the door and you can live with your mother tonight! I said she is the most ungrateful brat who lies and manipulates so that she can make me the reason she will be living with her mom. She doesn't like her body but won't do anything about it and actually makes me the reason for her misery. My DH turned to me and said I am sorry. I haven't believed you. I see it now. I see the selfishness and the manipulation and the pain that she is causing us. I am going to tell her that if she is really this unhappy and things are so terrible for you you need to leave and live with your mom now not in the summer. I actually went out of my way to make her favourite dinner tonight and she just had to cause more drama. I told my DH that I will no longer be around when she is over that she has disrespected me for the last time that gas lighting me is unacceptable and trying to make me the reason for her fulfilling her BM nasty agenda and blame me so she can justify no longer staying with her dad was the last straw. I told him I would no longer be around until she has moved out. Luckily I have a place across the hall so I don't have to spend any time with her. Honestly, I don't owe this kid a thing. She has made my life a living hell and I am counting the days until she leaves! I just don't want to be the reason but then again if that's what she needs to tell herself so be it but it will be a frosty day in hell before I allow her into my life again. I think a very long break might repair things but I'm sure that she will still lie and cause drama in any way that she can.