I'd get a second opinion from another doctor. Reschedule work to drive him to appts. Clean up his diet if needed. MAKE him follow all the instructions to the last letter.
So basically I'd make sure he would be at every appt and that he was following the guidelines. Then I'd expect him to get on with life afterwards as it is over.
Unfortunately if I sat him down to talk about how he was feeling I'd end up saying stupid things like "statistically you have a 35% chance of the meds not working". Or as I told my grandmother when she got her cancer diagnosis "cheer up, yours has a survival rate of 60%, odds are good". In hindsight, not the smartest thing to say but at the time I thought I was being helpful. Btw it wasn't and my mum was horrified.
So now I don't offer much emotional support as I regularly stuff up but instead try to offer practical help ie driving ppl to appts, cooking for them etc.
ETA - I'm similar to my dad in personality. Not much of emotional capacity within and my mum needed way more from him. They are both happier now with different people who fulfill their emotional needs. I'm not saying you have to leave your dh OP.