I second Jack, if she wants to live apart, let her move out.
The other stuff, that is also her problem to deal with. She may not realize for a long time the damage she is doing with the kids, but eventually, more than likely she will. Then it will be up to her to fix that.
What can you do? Be the best Dad that you can be. Be the rock for your sons as they will need you.
I do want to say, letting this happen, letting MLC happen, is not quitting. It is going on with your life, improving yourself, growing and getting stronger. It is rebuilding from the damage that the MLCer has done to you (because there is some, there is always some), and then being the person to be there if and when they do come out of it. If, by that time, that is what you want to do. By the time that happens, if you do the work, you will know if that is what is right for you or not. That is one thing you do have a choice about it this whole crazy thing.
If you rush it, if you just throw in the towel because it is easier, you will always wonder what if…
Do work. It is the best way.
You will see this on here time and again from those of us who have been around for a while, this, this craziness, really has been one of the biggest blessings in my life. Although I wouldn’t wish it on my worst enemy, I wouldn’t change it for the world.
"Acceptance doesn't mean resignation. It means understanding that something is what it is and there's got to be a way through it."--Michael J. Fox