You have such a good handle on what's going on for you. Your clarity is amazing, but, as you know, just because we understand something, doesn't make it any better. We still may not want to accept it. Your husband does sound a little self-centred with his remarks. It doesn't sound like he has much understanding or acceptance of MI, and if I were you, I'd want that to change.
You say you are "having to throw my depression to the wind for the next few days to unconditionally support him in his time of need."
Let me ask you this: what would happen if you didn't? If you just quietly kept caring for yourself and left him to do the same? He is your partner, not your child, after all.
I am playing devil's advocate here, and I remember that your own family does care for each other like this, but that's not how he operates. Just a thought.