If your choice is to throw away or try to clean it, put it in a hosiery bag (dollar store carries them) and wash it with a nonsmelling detergent and bleach with hot water. The bag will keep it from shredding. The bleach and soap will get rid of the must. Use a nonsmelling detergent specifically to make sure that musty aroma and its cause has been removed. After it is dried (throw it in the drier), remove it from the hosiery bag.