update

So, now it is May and we've had some good weeks but mostly the same.  It is horrible living with him, missing our old life, and seeing him act like nothing's wrong. He has done nothing to start working on moving out.  He is the one that has to go, he can't afford this mortgage alone, but I can.  I am resisting the call to just get a place for him, take care of the details so he can just go. It's hard to believe, but I think he would just live like this the rest of his life, just to avoid having to make changes, make decisions.  I feel so guilty for breaking up such a long marriage, for the tension that is always in the house. 
I just re-read my earlier posts and can't believe I am in the same place after all these months. I am alone again, he is out of town for a marathon for the weekend.  My chest feels tight all the time and I lie awake most nights thinking and crying, I think it's the stress. Meanwhile, he sleeps like a baby and keep planning more runs. 
I've tried to talk to him about my feelings, about what I think could make things more tolerable, but he just can't communicate like an adult - he avoids talking and won't listen. I'm convinced that if we stay together, it will not get better, because he doesn't see anything wrong.
I keep revisiting my decision, wondering if I am being stupid and selfish for causing us the agony of divorce just because I am not happy. 
I know that so many people have more painful, even abusive relationships, and I don't equate my situation to that.  I have been dealing with these feelings now for almost two years with no sign there will be any change.  I've taken actions to try to work on the depression and make sure I am making decisions from a place of clarity. I know that we cannot and should not count on changing the other person, we can only change our own behavior.  So, what is the solution then?
I've read some "fixing your marriage" type books. They recommend treating your spouse the way you want to be treated - with consideration, care, "be his biggest fan", do kind things - and if you do this, the other person will naturally respond.  Maybe I am doing it wrong, it does make him happier when I go overboard with the kindness and care, but he doesn't change anything about his own behavior.  Clearly I keep wavering between trying to fix this (due to the guilt I feel for breaking it) and letting it go. 
 I hope I am not back here in 6 months with the same old sad song. That would be pathetic.