I know how you feel. Its my first year in res next year, even thou Ive been in uni for a few years. That idea freaks me out too, but it my dorms, you can get a single room, that comes with a single private bathroom, that you share with 4 other people. Not bad, and I'll just be more careful to wash my hands after i use the restroom. Also, they are cleaned on a daily basis, so any lingering germs wouldn't survive long.
maybe your college/uni might work in the same way. Also, because I have IBS, a previous university was going to allow me acess tomy own private bathroom that I would not have to share. You could always talk to your doc and tell him to write you a medical note explaining your extreme anxiety, and they may make allowances for students in your situations.
but also, it might do you good to face it head on and just go. don't let this phobia stop you.. we can do this!
~*Jill*~ Teacher, Advanced BSc in Psychology
"You can unlock any door as long as you have the right key". Mrs. Brisby, Secret of Nimh