Ouch!! Sorry to hear about this... I know it will be a chore, but now you are in damage control. Save what you can and cut the negs out of the sleeves. I had to do that some weeks back after my laundry room dumped water from the floor above into my darkroom! Granted, not as many negs as you, but enough to be a PITA!!! CUtting the negs out is theonly way to go without risking damaging your negs. Clothes pins and photoflo are now your best friends. I would string out some string across a room somehow and create a large drying line, or 2, or 3!! What you need is SPACE, lots of it if you can manage it so you can just start washing and photo-flo-ing and hanging to dry. It's tedious, but can be done. Good luck. I fear that some negs may already be too long in the water and the emulsion is breaking down. Let us know how it all goes.