My complete sympathy, osso.
When I moved from a large Cal. Bung. to a tiny Victorian terrace house a few years ago (with 3 cats!) I HAD to be ruthless! No choice. I had to change to smaller furniture, too. Smaller EVERYTHING!
I actually made a lot of $$$ by selling some semi-treasured books (which I hadn't looked at for years, BTW) to dealers. Hard at the time, I can tell you! The rule of thumb I used was: Have I looked at this book in the past 5 years? No? OUT, then! <gulp> I still have too many, but no longer purchase expensive art books, etc. .... The internet has been used much more for research & "just looking" purposes ever since! And, surprisingly, I DON'T miss many of those books at all. It was something about knowing they were there on my shelves, like old friends, that tied me to them.
Now, did that help? :wink: