It's so sad that you clearly are at breaking point yet after venting on here in a shocking way that shows you don't have limits in the way that would be expected.... And yet by the end your actions and plans are all about keeping everything exactly the same, and going to great lengths to keep it that way.
You are the only adult in this situation and you are cracking up. You need to act, not 'lie through your teeth' about it.
Mind boggling. Staying the same means everything will stay the same! That means sentencing everyone in this fucked up situation to do today over and over again. The only person who can break out of this torture is you. Not your eldest daughter. Not your 12 yr old. Not your 14 yr old. Not dd1s father. Not your ex. No one else. And yup, unfair, super unfair, but you can do nothing because it's unfair, or you want others to suffer, or you've already decided nothing will help. And do nothing. Condemn everyone to life imprisonment in hell! Or stop raging and channel that energy into getting out!
Basically, you're the key, use it or don't, but don't bar the prison gates and patrol the towers and then whine about being locked in a prison with these horrible ungrateful people.
I know it's hard. But you have to change. For your daughters, the ones you still love and the other one you 'hate' and blame. For yourself.