I just wanted to chime in and say that although our circumstances are obviously different, I can really relate to a lot that you are going through.
My stepdaughter (17) just finished 7 weeks at a wilderness program and is going to start at a residential treatment center next week. It's been years and years and YEARS of hell with her. I also totally get the extended family thinking that we're just being mean - I was the scapegoat for her behavior for YEARS. I was blamed, even by my husband, and it was truly horrible.
She's home for a week while we get everything squared away for the Residential Treatment Center (RTC) - my hope is that she'll be so happy to be using a real toilet and sleeping in a real bed that she'll honeymoon through the week and then be gone for a LONG time.
Welcome to the boards. I truly don't know where I'd be without the support here.