I would say to no longer "diagnosis" your H by telling him he's depressed.
When he said he was done and no longer wanted to be in the marriage, simply say "I don't buy it. But if you feel that is what will make you happy I won't stand in your way".
Opening the "cage door" will make whatever "burden" he's feeling lighter, while telling him why your think he's behaving a certain way etc... probably just makes him more angry.
Melissa is right, whatever he's going through has nothing to do with you. Continue with your PMA and taking care of yourself.
me: 30 H:30 tgthr:7 m:4 no kids 5 counseling sessions initiated by H as a LR: Oct 2012 long distance marriage b/c of work since Nov 2012 official BD: July 2013 nothing filed 1/1/14 I dropped the rope