Wow, your sitch is a lot like mine. Married 23 years, same pattern of detachment, not wanting to do ANYTHING with me, just shutting me out. dropped the bomb in Sept, I agreed that it might be good to spend some time apart. He went out and bought a house, (supposedly as a good investment, v.s. spending money on rent) moved out Dec. 1st. So relatively a short separation, although he made it clear that before he closed on the house, that we were "Separated" (no sex, sleeping downstairs, not spending any time together, etc.) He too says he has a buildup of anger and resentment from years and years of nagging, rejecting him sexually, occasional verbal abuse on my part, all of which I fully own and have apologized over and over for, and have been making big changes. Like you said, none of the big things that are "deal breakers" in my book. No affairs (that I am aware of), no physical abuse, drugs, drinking, family problems,nothing like that. Although he left 4 years ago, claiming unhappiness, but returned home after 2 months.
In the past 4 years (after his initial leaving), we've been under a lot of stress, with 2 teenage girls, (one of who has been in trouble a lot and the oldest just left for college) his job has had a lot of turnover (new bosses) plus I had non-invasive breast cancer which required surgery and 6 weeks of daily radiation, and his father died last May. So, yes, it has been stressful at home for all of us, and I dont handle the stress well, and apparently took it out on him. I dont deny the inattention to our marriage, it just sort of got swept under the rug.
My H seems to want his own life too, being able to persue his sports and hobbies, which are all important to him, and a major source of disagreement with us. He spends more time with his buddies than he does his family, hunting, fishing, golfing, you name it, plus he is out of town a lot on business. So the definite disconnect was there long ago, but his hobbies and a demanding job take prescedence over our life. Since moving out, my H is detaching more and more too, after spending quite a bit of time together--and having a great time--at respective families over the holidays to keep up appearances(they dont know about the separation, only 2 close friends know--at his request to not broadcast it to friends and family). He basically wants to do his own thing.
You have more positive things going for you though--at least he will attend counseling--mine wont. Says he's not ready for that (?).He has rewritten our entire marriage, saying he was "miserable" and that we had no good times. My H too is depressed, I think, but wont seek help. God knows I am! Thats another thing--Xanax is a wonderdrug for me, taking the edge off so I can function. I, like you, was a complete mess for weeks. I know its temporary, but it definitely helps, along with my C. See if your Dr. will give you something to help you function.
Secondly, I have vowed NOT to bring up the R again, as it seems to agitate him--he wants to keep things light. Easier said than done, I know, but after backsliding many times with poor results, I think they just don't want to talk about it, so we must shut up. His other major complaints is that I'm too needy (working on that) and trying to push for answers/decisions. I would recommend to you that you just DONT CALL and DONT PUSH--those 2 things have definitely been my downfall. ITS SO HARD, I know--I seriously get panic attacks.
Mine started out by saying that he didnt know if he wanted to be married anymore, to now he wants a D, but is not ready to take that final step. I dont know how it got progressively worse after he moved out, but it seems I've pushed too hard. So, lighten up, dont make conversations long and drawn out, Ive begun to put a self-imposed limit on phone conversations, because I tend to try and keep him on the phone just because I'm desperate for contact.
So, I'm with you--I'm a mess and lonely too, and I panic when I think of the future alone. Try to take it one day at a time. Hang in there and keep me updated. Let me know what you have been doing that gets positive results. I dont know how they get over the anger and resentment and just start fresh--thats what I want to do, along with MC.