I am a relative newbie, but I read your thread and I am so sorry you are going through this. I am curious if you have not dropped the rope what exactly are you doing? Being dragged behind the out of control car because you are still tied to the bumper? How does this in any way help you prevent it from going off the edge of the cliff on a regular basis? I think it only makes you feel connected and in control but really just causes severe damage.
First and foremost if you are not detaching completely and dropping the rope how can you possibly heal, take care of yourself and your kids? I mean they already have a mother who is completely out of control, right?
Second if you take enough damage while you are trying to "fix her" you may find you have nothing left if and when the day comes where she finally wakes up and wants to repair your relationship. Trust me you may not realize it but all these events and hurts are slowly eroding your love for her, like acid. I know from experience (and believe me I detached lot more and much faster) that even now I am realizing how much damage I took over the past year and how much it has impacted my love for my wife. And she doesn't seem nearly half as bad nor has she done anything nearly as whiplash as from reading your story so far.
I hope you realize this is not meant as criticism or "obvious" statement, rather as a fellow traveler having a lot of empathy and trying to tell you, as counter intuitive as it may seem, dropping the rope and not rescuing her is EXACTLY how you help her rescue herself. Obviously she is still deeply tied to you and need something or find some form of relief/safety from you. But she seems to be using it to avoid confronting her demons.
Hang in there, take care of yourself first. Detach and heal, or there won't be much left of you or your relationship when the time comes and you do have to re-connect and re-build. Hope this helps.