Lt -- take her up on it. Quit worrying about what she's doing, how you can help her, etc. You can't. DETACH. Think about what you want out of YOUR life and go get it. Seriously, why even try to attach/connect at this point? You've done everything humanly possible your way, and it's not working. Try something completely different: be outwardly happy, be the positive lighthouse, keep the road home for her paved, but just be there, not pushing, not pursuing, not trying to demonstrate anything, just letting her be in her cranky, complaint-filled world, if that's where she decides she wants to stay. She's "so dead inside"? Not your problem, brother! That's entirely on her, even if she wants to say you're responsible for her feelings. That's buck-passing scapegoating no-personal-responsibility BS.
I know from sad experience how impossible the in-house separation is, so I hope you don't take any of the above as preachy. I never could personally manage what I'm advocating, but I think it might have helped our sitch had I pulled it off, and I KNOW I'd have been a lot happier a lot earlier.
Me: 46 W: 44 Married: 17 Together 21 D13; S10 BD: 03.03.15 (Not attracted to you) Almost 2 years trying, alone, to save marriage Status now: Divorced (effective 06.13.17)