Hi Ahn,
I too had this problem. I slept propped up with cushions and pillows, and used gauze in my cheek to keep my mouth open slightly. I lay my head on an old towel and simply allowed the mucous to drain out onto the towel. It was the only way to get any rest. I still needed to sit up and spit, and rinse with a salt water solution, but it was less often. The mucousitis is a very bad side effect, but it will improve once the treatment has finished. I imagined that every time I spat out the mucous I was spitting out cancer cells.......just to help get me through it. All you can do is support your husband, and make allowances for the fact that he is exhausted and in a lot of pain. God Bless X