It was so great to read all of your responses! I thought I'd check in about my process. I had a wise friend remind me that I love my books, they are part of who I am and how I function, and it's okay to keep a collection if it means that much in your life. She is right, I really didn't want to get rid of all of them. So here is what happened:
First, 26 boxes of "XHs books" went back to him. Swiftly. Along with a few stragglers that showed up later.
So far I have kept all of the kids' storybooks, at their request. If we don't have space in the new house we'll downsize then.
I also kept one large bookshelf full of homeschool reference books, workbooks, nonfiction reference on interesting topics, and curriculum. Ditto -- will downsize later if we need to.
We have two small bookshelves in the hallway with kids and young adult chapter books. The bookshelves are coming with us, so the books can, too.
I collected all of the remaining books and put them all together in one room with a big table for sorting.Then I bought a bunch of extra sturdy bankers boxes at Staples, with lids. I sorted all the remaining books by topic and tried to limit it to one box per topic, but a couple of topics merited two boxes. I labeled them by topic.
8 boxes went to the used bookstore, paperbackswap, friends, and a charity book sale.
There are a lot of books. I think I must have about 25 boxes. They now live on shelves in my garage and I can easily find what I'm looking for because they're shelved by topic.
When we move, if the space won't support that number of books, I will downsize further, knowing exactly how much space I have to fill.
I also sent 3 boxes of CDs to XH. The remaining CDs are in a storage cabinet waiting for me to have free time to go through them, put them in thin sleeves, and store properly. Low priority under current circumstances.
It was a huge, huge project and took a number of days over a few weeks. I am glad I had the space to spread it all out and assess all at once.
I realize that ending up with 25 boxes probably doesn't sound like decluttering, but the number of books in the house went down by about 60%, and I consider that a success for now!!
Well done mama! you said that it probably doesn't sound like a lot when you still have 25 boxes left.. But you forget that the first round of decluttering is always the hardest, so IMO you've done brilliantly. Onwards and upwards!