How do I de-mold my book?

http://blog.lib.uiowa.edu/preservation/2009/03/05/cleaning-moldy-books-and-magazines/

http://extension.missouri.edu/publications/DisplayPub.aspx?P=GH5928

Both have good stuff on cleaning & preventing this problem.

you could set up the book over a tray of very diluted bleach or hydrogen peroxide and dip the offending pages for a while until the stain disappears, then blot as dry as possible, and finish drying, open to the damp pages, outside in direct sunlight.

The stains are most likely there to stay, but using some Lysol on a cloth will do the trick (for the mold)! I live in humidity, so I am familiar what you are dealing with.

It needs to dry out completely.

Separate it from all other books as the mold can travel easily.

I’d just let it bake out in the hot sun for a day or two. I’ve put them in the oven before (but you need to keep a close eye on it).

The staining will not go away.

Look at this—Smithsonian research on paper conservation
http://si-pddr.si.edu/dspace/bitstream/10088/8141/1/mci_JAIC1992-DvR.pdf

A paper conservator can sometimes remove foxing, but generally it’s only done if the book is a valuable specimen.

Usually by method similar to the bleaching described above, in case you want to try it yourself on a less valuable specimen.