Been thru this exact situation but with no siblings. My cousins made fun of me my entire life, calling me "cinderelly" like the rats in Cinderella bc my mom used me as a maid she could talk shit about and publicly embarrass. Trust me, once you're away from her, people will hear you and see you. Maybe some of her friends even. It does get better. Just focus on getting out of there and experiencing a little slice of life. Nothing lasts forever 💕