This is a tough one, OP. There's no right way. I would be led by him- what does he want to do, how does he want to spend this time? Some people pull in or are too ill to do things, others are still up and about til very late on. Don't be frightened of him, I know this sounds silly, but often people are scared to be around dying people, but they are just people, as we will all be at one time, at the end of their lives. Think about what he likes, what he wants, he might want to talk things through, he may want to ignore it all, by being led by him it will help you overcome that feeling of how you need to be.
Put in place your own support system, so husband, friends, work counselling, therapy, somewhere you can put your own thoughts and frustrations and worries and sadness so that you aren't carrying it all into the interactions with him. Extra help with the kids so you have some time to focus on this.
It's a hard time, OP, but you will get through this.