Ask the doc or pharmacist about crushing meds. Anything that is time release you cant crush. Since he has a feeding tube, use it for meds too. Ask the doc for liquid forms for things. I use my tube for taking all my meds. Is Tom using the fentanyl patch? If not, and he is in pain then this would greatly help him. Fentanyl is the strongest pain med there is, they range from 12.5mg - 150 mg doses. It lasts 72 hours and then he would only need a pain med for break-thru pain.
You are doing a great job with hydration. Keep it up! He may get tricky and not drink like he should, dont be shocked. There are lots of stories about patients pulling fast ones on their caregivers and medical staff. One person filled their pockets with stones before getting weighed. I would wear heavier clothing on weigh in days. Darn nurses caught on to it and started weighing me everyday after I had changed into the hospital gown. Then they started making me bring my formula with me and do feedings right there after my radiation appointment.
So far it sounds like you both are holding up. Many cancer patients and their caregivers too end up taking anti-depressants. I was prescribed some and took it for only a few days. Tom is a doctor, he should know its ok to use these meds. Im sure that being a doctor also makes him harder on himself. We are our own worst enemies!
Have your husband check out OCF. It might surprise him to know he has 'friends' here pulling for him

Keep up the good work, you are doing great!