i'm a newb here and am not personally going through this (though my son is, we're at the beginning of his journey), so i'm in absolutely no place to give any sort of advice, and i wouldn't blame you if you quietly rolled your eyes and moved on, or even told me to stand down and keep my mouth closed, and if you said that, you'd be well within your rights.
but your comments are of concern to me, because it's although quite clear how scared, helpless, and angry you feel, and although it's also quite clear that it's valid for you to feel that way, the hopelessness threading its way through everything you're saying worries me. the fact that you casually mentioned your daughters are 'tired of hearing' about this indicates that you feel alone and desperate, in addition to scared, helpless, angry, and hopeless.
i'm guessing you wouldn't want to talk to anyone about this - a professional, i mean - but i feel as though i'd be remiss if i didn't suggest it (though i'll allow that you probably already have tried, or already do.) i'm not usually the 'therapy! it's the solution to everything!' person; in fact, i'm usually the opposite. but you're dealing with something patently awful, and your resulting depression and loneliness is only going to pile on the weight you're already carrying. so if you'd at least consider speaking to someone - even if only to vent, scream, cry, feel less alone for 50 minutes a week - it might be worth it. hell, you can pm me, and vent, scream, and cry to ME, if it would help take off some of the emotional pressure.
my heart goes out to you, and i'll be thinking good thoughts for you. i hope i didn't overstep, and i hope i don't sound stupid. it's just, your desperation and loneliness kind of screamed at me through your comments in this thread, and that's of concern to me, and i guess i just wanted you to know that someone heard it.