Jackie, I would like to second some of the suggestions already made. I would first take the books to your local guild and give them first choice. We have had folks do this at my guild meetings a number of times. Not all books were taken but the pile was significantly decreased.
Donate to your local library. My library has a book sale 6 times a year and crafting books are always in demand. The library sells them from 25 cents to about $2.00 depending on hardcover, soft cover, age and condition. The "profits" go to support the library's efforts to purchase new materials for public use.
I understand how painful this process is, but in the long run, you will feel more free and will have in your hands only what you love and what you will use in the next stage of your quilting life. I had to do this when I moved from a house to a condo. Buy a box of good tissues and dig deep and keep only what is meaningful and useful to you. Best Wishes as you downsize.