This sounds more well-thought out than your earlier posts. I'm not sure now is the time for you to be making a decision like this, you've even contradicted yourself in this thread. You were upset w/ DH for saying no, possibly partially because of working more than one job & possibly taking on another while he is disabled & not working, which you think you may be resenting him for. Yet you're claiming too much time on your hands is why you think you need another dog to take care of.
I'm not pointing that out to be hurtful, but to make some connections that don't seem to be obvious in your mind right now. Step back, take some deep breaths, give yourself some time to get your legs back under you again. Working at the shelter is a wonderful idea to fill the ache you're feeling right now. Down the road you may find yours or your DH's minds change on the subject.
Maybe now might be a good time to count your blessings, give your mind a chance to dwell on the good things you've got going on. It never hurts to put a little positive in your outlook and may make you feel a little better.