I can't give you advice except to say I hope you can follow the advice these wise warriors are giving because they have been there and done this and I see them share their heartbreak and care over and over with others who are currently going through this kind of struggle. Little by little people come back and say that the advice given was right on. Of course it has to feel right for you, but when it is a new behavior for us it helps to have the encouragement from others who have survived all of this and have had to make these kinds of choices. In my own parenting area I find that really a huge help for me to take steps I had not ever taken before.
Thinking of you, wishing you serenity as the prayer says. Hoping this will actually be a wake up call ....at least the beginning of one, for your difficult child.