When your H is down, just leave him be (unless he wants you there). Please don't ever say another unkind word about yourself in those cases (or in any other case!).
I sent my now-H way too many letters as we were breaking up (mostly emails). There was one thing he actually liked - I found that out later. The one where I listed a lot of the positives for us staying together (I listed 100). He told me that that was one thing he did want to keep (not sure where he has it). It wasn't emotional, it was just a practical list of all the good things from our R - stuff we enjoyed together, etc.
I don't know if it would work for you - but instead of all the negatives, you might want to accentuate the positive in that way. He keeps thinking about the negatives, and maybe he'd look at a list if he had one.
Anyway, just a thought. It is good that you are working out - I haven't really gained appreciable weight in the past year, but haven't lost any more either (I want to lose 40 more pounds or so). I am trying to add more strength training and core exercises, I don't just want to be thinner - I don't mind how I look, but I do want to be fit.
Focus on your overall health - not just your weight. I know that if I do that, the weight (or at least much of it) should come off.
I know that if I do that, the weight (or at least much of it) should come off.