The slightly contentious observation I'd make and at the risk of appearing judgemental SJ (which I sincerely don't wish to be) is that it seems like you have not been leaving your H alone for very long, over the 2 years, so he's very entrenched in his cave.
If anything I'd be encouraged as he's still with you, it's just that you've got into some tricky positions that gently need maneuvering out of. Frankly, a BD is acting like someone who is ill-informed and in a fog, which you aren't SJ. Maybe it's better to think of your sitch as being at a point where the Last or Last, Last Resort Technique (LRT) needs to be potentially employed and then you can adapt and fit the DB strategy around what you do, rather than something potentially a bit maverick. Have you got and read the book yet?
The detach element to DB applies here (read up on it on here, or in the book) and until it's strictly adhered to, or as close as you can get given your sitch, you'll not make any real or sustained progress.
You've agreed to one more month before deploying a BD (still think this approach is wrong), make that a month where you go no where near his cave. Keep as big a distance as you can between you and your H, no crumbs, no nothing (sorry Azzork). If you get some movement from him, leave a mere morsel nothing more, be very frugal, to encourage more, but if you leave nothing you'll get more movement anyway IF he's ready to talk. Fight any instinct to reach out or fix him and he may turn around but if you don't give him space he'll stick where he is, almost guaranteed.
- Nobody has ever learnt anything important from happiness and success; problems make us grow - Consult your plan, not your feelings - If you haven't set goals, how can you expect to achieve anything?
