I think a rescue mission is where this is already at.
The only thing is WHO?
Rescue himself and the kids and get out of the crossfire ASAP? Or try to rescue the wife also from being all "bdsm drunk/addicted" right now?
She doesn't sound like she's thinking right. Prob is -- does she even care? And does OP even want to try to rescue her or is he done with this relationship?
It's a sad situation. I'm so sorry CrapEndofTheStick.
But really before you can decide on ANY course of action here you have to look inward and decide how much you love your wife and if that is enough to even be bothered any more to try to rescue her. It won't be easy or pretty.
And if you don't have it in you, do the right thing and get the kids protected and your protected. Because even if you DO try to rescue her, you have to do that part first anyway
. Put your own oxygen mask on first.
THEN see who else on the crashing plane you can aid if you are still willing and able.