It's late and I want to go the gym tomorrow morning before work, but really wanted to chime in tonight. I can relate to your intermittent detachment. Some guys have done it much better than me - lovingly detached - and earlier in their sitches.
Me, I didn't really truly DETACH, until my W was in the D process and I had been GALing for 6 months - and it was still hard. Mine was more out of necessity - that I'd better get my sh*t together because I was going to be by myself soon. But it was still very helpful at that point - to get me through the last few months without going nuts.
But like I think I've said before, there was never an OM in my sitch - not sure what I would've done - I would've been crushed to say the least. And sometimes, I think it would've made it easier to go along with the D - at least in my mind. I'm not sure if I could stay married in the presence of an OM, since along with the new self love comes a new self respect.
What's good for you is that even when your detachment is weak at times, the weak times are getting shorter and therefore you are getting stronger. I know this isn't easy, with the OM and being in limbo. Sometimes, I think I have it "easy" knowing that the D is coming for me.
Stay strong. Keep reading. In addition to strengthening your body, work on you mind. That's one of my goals - I'm doing some yoga and want to start meditating.