Hi OWW
I don't normally post so apologies if you feel I'm intruding but I did just want to mention a thought to you.
First of all, I think you might (note the cunning caveat) be getting through the worst with LM and he's now realising, and admitting, what an arse he's been; he's just not doing it as articulately and thoughtfully as you would, probably because he doesn't know how.
With my ex I found that when I was overwrought and trying to be heard I often couldn't counter his points well during any "talk" and I would then end up off track, missing my point or just petering out and then regretting it the next morning.
What worked for us was that I would write a letter, addressing the points I wanted to make and then give it to him to read through while I was there. The first time I did this I explained to him that it took the emotion out of the message plus it had the advantage of making sure that he could re-read what I was trying to say, which really helped. He was a bit geeky and I think he really did absorb the message well that way. I only ever used writing for the big deals, so it was only a few times, but it did work and he did tell me he appreciated and preferred it. Given that he's now an ex, maybe I should have done that more often 
.
If I were you I would hang in there, just a bit longer - I agree with what you said a couple of threads up about the "what ifs" if you didn't. While I agree with much of Lubey's sentiment I wonder if this is his way of saying the big sorry - he just doesn't know how to do it properly.
Do bear in mind, though, once the shop is open, there'll be new and different headaches to distract him so watch out on that score. I have everything crossed for you.
Good luck!