Poor you. And poor him. How old is he?
Is he tapering off the medication, rather than coming straight off it? It would be a very good idea to do that.
CBT alone may not be enough. How much does he want to get fully well again? I find it's a lot of effort and only really works if I do a multiple-action recovery.
Top of that is daily exercise, ideally outdoors. He may need to start small and may need encouragement - could you walk with him every day for half an hour? Or get him to walk the dog if you haven, r a neighbour's dog if you don't?
Daylight is really important in case SAD or Vit D deficiency are an issue. Do you have outside space where you could get him to have breakfast or lunch or early dinner with you, rather than indoors?
Is he up for changing his diet a bit? (I know how hard this stuff is, and how difficult it is to feel and stay motivated as all this is so much effort, but without the effort, he may take far longer to get well.) It's important to have more than 5 a day, and to eat foods which replenish the chemicals that are lacking in the brain when you get down. Turkey's supposed to be really good for this. Chicken's quite good. Salmon and tuna too. If he's veggie almonds, walnuts, chickpeas, brown bread and rice and sweet potatoes help.
Also, he may need a small prod to get back into the community. A simple job, like helping out at a charity once or twice a week would be good. it'll make him feel valuable and like he's contributing.
The biggest help I found was to realise you don;t have to want to do something at all, not even a tiny bit, in order to do it, if you know it will help you get better. There's no need to want to shower daily, clean your teeth, go for a run, work at the food bank etc but if you do, regularly, then you end up feeling better.
Try having soothing or upbeat music on (ideally stuff he likes and would choose) and same with DVDs and TV - go for silly/funny stuff not grim dramas and news.
Give him tiny easy jobs to do - lay the table or fold towels from the laundry etc and bit by bit increase them.
Sorry if this sounds very bossy. It's taken me years and years to work out how to climb back out of illness each time it hits. It's so draining for you and him.
One last thing - depression is massively a physical illness. I think people don't realise this. If his heart or kidneys had malfunctioned you'd expect him to rest a lot. His brain has malfunctioned. It's a crucial organ, just like any other, and it governs the entire body, so when it stops working, everything does. It will leave him feeling very tired and weak. Let him convalesce. Let him sit in the garden and snooze. Let him have early nights but try and get him out of bed in the mornings for a shower, a walk and some food, just so he doesn't lie there all day. Don't expect him to be able to snap out of it, anymore than he could snap out of recuperating from a heart attack.