God, it's hard enough to drag ourselves through this, let alone see our kids suffer. I am SO sorry D is in that place and I hope you can get her help soon. Depression in teens is - well, you've seen it- a very unpredictable combination.
I'm so sorry about the references to the OW too- disgusting. He has just shown his worst side through all of this, hasn't he? I wish there was something more I had to offer you, but you're in my thoughts and for what it's worth, I think you've handled the most disreputable behavior in a classy way, which you will never regret and which your kids will remember and gain strength from. I was (and also married) a kid who for all intents and purposes was only raised by my mom even though dads were around, but they were nasty/uninterested. We both turned out pretty good and both admire the hell out of our moms (and did fine with ass dads). It's not ideal, it's not what we want for our kids, but you will get them through this and come out the other side. Probably seems impossible now, but it will happen.
In the meantime, there's a lot of people here who care about you-
(((Luv)))
When the men on the chessboard Get up and tell you where to go; And you've just had some kind of mushroom And your mind is moving slow; Go ask Alice... I think she'll know.