Complete disfunctional family

I would have to go back four generations to give you a complete back ground but in short, my mother (Self absorbed, taught the kids to lie, egged on fights between them, preached that the parents were bad for working and that she loved them more because she lived with us to take care of them so they could take care of her, etc – my step father passed and we got stuck with her as she was a hippie that never planned for her future and thusly had no money and no one to help her at age 49 when we got her) lived with us during the child’s age of 5-13, we had a second - older bipolar daughter who mentally and allegedly sexually abused this child, and they had a part time step sister who was mean to her because she resented her dad living with us after the parents’ divorce. We have been together 11 years now and my child has been slapped by him twice in 11 years (for her language and disrespectful speech to me). She let her room and bathroom become so filthy that we have had to go in many times, this last time we went in and pulled out 2 boxes of dirty dishes, 5 bags of garbage and, a mountain of laundry.

Both the grandmother and sister have been removed from the home over the past year and a half by us to help the child and her step sister only comes over on some holidays. Our Medicaid psychiatric options are slim and incompetent. I was disabled in a car crash and live with chronic pain and limited mobility. She has ballooned up to 250 lbs at 5 ft 7 and began developing all the problems associated with it. She has missed over 135 days of school this year and I had her placed on Juvie probation for it. One minute she loves us, the next I over hear her lying on the phone to someone about how we treat her so horribly, hit her, punch her etc. The child has never done without any material things (other than when instructed by Medicaid Dr.s). We don't hit her, we don't mentally abuse her, we are always there for her especially since I have stopped working due to my pain 3 years ago. We removed the sister to another state and the grandmother to another county. She has abandonment and jealousy issues with her biological father accepting her sister but not her. However, my mate has always been there for her. I am worried that she is going to say the wrong thing to the wrong people and either get one of us killed (as has been threatened) or get us needlessly investigated by the Dept. of Children’s and Families who are tired of her groundless complaints and may remove her from the home.

What are we to do? Write a life story book and submit it to Oprah begging for help and wear bags on our heads on TV or let her continue to spiral out of control and wind up like her sister on drugs, with green and purple hair and tattoos all over her body. ODed multiple times on DXM finally thought she was the new Jesus Christ and took a knife after us all, hence why she is now in VA with her bipolar father (both are unmedicated).

We sleep with a deadbolt on our bedroom, I am up all night checking doors and making sure she is in the house, sometimes she is so sweet, caring and loving and the rest of the time she is a foul mouthed, spoilt, bitter, self serving, heartless monster.

We have to have a life at some point, I've only had friends twice in 17 years, and we are too embarrassed to have any come over so we avoid those situations. I love her with all my heart and know she is still young enough to be helped but can't afford to pay for a real psychiatrist; all we get on Medicaid is interns who I have to write amendments to their reports because they can’t even get the facts straight when they are taping the sessions. I am not mentally or physically ready to go back to work, I still need another year and I need to update my skill set to the current world to return to my profession as an executive assistant.

Should I give up and let her go? Should I be the poster woman for the modern sandwich generation family in the time of the talk show route to get help for poor people hence hindering my career and our financial stability? Thank you for your time and input.

Desperately,
I’m Stumped!