okey first off you dont no that you have been placed in the room just yet right? so until its confirmed try not to worry about it too much. Now if it is confirmed all you can really do it try and get along. i understand your situation, i hate being put in a situation where i have to interact with complete stranger, i'm a very shy person, although i dont have an a anxiety disorder which i realise would make the situation so much harder for you.
In my first year of college i was placed in a flat with FIVE complete strangers, so as you can imagine i was freeking out slightly. Anyway i managed to get along with them okey but i only did that by trying to talk with them and get along with them, so basically just try ad get along with them, if you feel your starting to really panic try stepping back from the situation and take some me time.
Just try not to get it into your head that your not going to get on woth these girls before you meet them because if you do this you will find it harder to get along with them, and if/when you do meet them just try not to panic.
hope it goes well for you
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To be forgotten is worse than death