He sounds jealous to me? You are in school and working two jobs and doing your thing but I haven't heard of any things that he's doing/interested in? He could just be a bit afraid you'll grow away from him, start to make more money, have a more interesting job, that sort of thing and he'll only be good for paying bills, not a very exciting way to think of one's self?

If he won't talk, there's not much point in speculating on what he's thinking/feeling? You pulled out of him that he does not want separation or divorce and it appeared to make him angry talking about it. He has said "it" is all your fault. To me, how he feels about you and what you are doing appears to be what's at fault; not literally "you".

I'd get proactive and ask him to go to a few therapy sessions together so you don't have to do all the work of trying to figure out what is actually wrong. If he will not go, that will tell you something else. If you want to live that kind of life, I would just shrug and keep doing what you are doing. I would move back and if he wants room to think or whatever, he can move out as he offered to. My advice would be to take him up on what he gives you and not buy into his drama. If he doesn't get talking as much as you'd like or help resolve his issues, then I would think about if I wanted to do something else for myself.