AITA for being upset?

I (22 F) share a room with my sister all my life. My brother (24 M) is getting married and moving out this August. He told me months ago I would have my own room and it was something I was really looking forward to, my own space. Today he tells me he needs to keep the room because what if he comes and visits and needs somewhere to stay (he’s moving 30 minutes away.) He told me that it is his room regardless of whether he lives there or not. AITA for being slightly upset about this? Now i’m being forced to find an apartment and move out.
AITA for being upset?
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