AITAH for moving out without telling my parents after they gave my room to my stepbrother?

I (20F) still live at home while I’m in university because it’s much cheaper than renting. I work part-time and pay for my own phone, car insurance, groceries, and contribute towards bills when I can. My parents have always said as long as I’m studying, I’m welcome to stay. About a year ago, my mum married my stepdad. He has a son (17M) who comes over every other week. At first everything was fine, but my stepbrother kept saying he hated sleeping on the sofa bed and wanted “a proper room.” A few months ago, I came home from work and found most of my things packed into boxes. My bed, desk, and wardrobe had all been moved into the small box room that we’d always used for storage. My parents told me they’d decided to give my bedroom to my stepbrother because “he’s younger and needs the space more.” I was completely blindsided. They hadn’t asked me or even warned me. My new room was so small my desk barely fit, and I had to keep half my clothes in boxes because there wasn’t enough storage. I told them I thought it was unfair, especially since he only stays over every other weekend. They said I was being selfish and should be happy we’re “blending the family.” I stayed quiet for a couple of weeks while looking for somewhere else to live. One of my friends had a spare room in a shared house, and the rent was affordable, so I signed the lease. The day I moved out, my parents were both at work. I packed everything with the help of my friends and left a note saying I appreciated everything they’d done for me, but I didn’t feel like I had a place in the house anymore. My mum called me crying, saying I was trying to tear the family apart. My stepdad said I embarrassed them because they came home to an almost empty room. Even my stepbrother messaged me saying he never asked for my room and now everyone is blaming him. Now some relatives think I massively overreacted and should’ve talked to my parents more before leaving. Others think they crossed a line by moving all my stuff without asking. AITA? I put this on here since I need a opinion and can’t use the AITAH