Suggestions about the "doomed" spew? Maybe treat it as spew and do not bother to process it when he vents it to you or in MC. You can only deal with your own present behavior and your own future behavior at this point. The past is becoming increasingly irrelevant and distorted in looking back through various filters. It's a way to avoid stepping into now for your H.
h4l: My advice to anyone else would be to let him go and see if that is really what he wants ultimately, but the pain on being on this end of rejection and blame is too painful.
Then let it go for at least this week and take some space before you get dragged down too far by his rollercoaster. The back and forth is excruciatingly painful, especially when coupled with blaming spew. You don't deserve it. He did half of it and his own psychology continues to shore up the wall which perpetuates it. Time for people to move forward. He either will or won't. Detach if possible. It's really hard though, I know. Almost impossible with your daily contact. I wish you could reduce the daily contact for awhile.
Maybe Kalni has some advice. I noticed on her thread that things seemed to get tough and stuck for her H during some of that MC.