mtq:
Same happened here in 1996 when my town got 15" of rain in 24 hrs. Basement flooded with essentially groundwater. I lost a lot: ACE, NASWA, DSWCI, cassettes, some QSLs...
My advice is to set priorities, because what isn't moldy now may be moldy in a short time. I remember having to set priorities concerning what could be saved, and what wasn't worth the effort. I decided that I would try to save those things which couldn't be replaced. In the area of DX that meant a bunch of QSLs and my collection of Chicago Area DX Club bulletins, at least the ones from the time when I was the editor and publisher. TBH, I never felt a loss after being ruthless in the cleanup; there is always new junk waiting to be collected.
I think ff said it best: "I guess most of the pain comes from the shock rather than from the actual loss."
Best of luck in a speedy recovery.