Have you tried explaining to your roommate how much it bothers you?
Two people sharing a space need to be able to communicate about what they need. (Easier said than done; my current roommate and I don't talk at all.) Unfortunately not everything can be solved by drawing a line through the middle of the room.
Restaurants used to have "smoking sections" and if you didn't smoke you sat somewhere else. Of course that doesn't work because the smoke goes everywhere.
I guess I'm not being that helpful here, but if you have to live with this person you'll need to respect each other's right to be comfortable in that space. If they won't listen, maybe a parent could facilitate that discussion? Also I know it sounds dumb, but drawing up an agreement can really help. I'm sure both of you have things that would make you uncomfortable in your room, so agreeing on some basic rules can make everyone more able to live there.
I say this without having had much success in this area either, but that's because in college you have to live with a total stranger which makes everything a thousand times worse.
I hope this works out for you.
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Diagnosed ASD, ADHD, Tourettes age 5
They/them
Feel free to PM me--I like to talk about most things other than sports