I need an answer as to why i received a mother who makes me feel like an outcaste?

Buddhism teaches to respect parents. I do follow. But when ever i bow down our relation with my mother, she constantly tries to bring me down. She makes me feel bad for the way i look. I cannot change my skin color or my height. She nags about my appearance. My childhood was ruined and now she is making me depresses by saying no guy would like to marry me. It is getting hard to listen to her day by day. I am a person who upholds goodcharacter above anything. I can never say a bad word to anybody's face. Yet i am facing this almost everyday by my mother. When she fell ill i could not leave he and i was the one who suffer her illness more than her mentally. I feel bad as why she cannot see me as a daughter and love me when all i want is to make her happy. What mistake have i done in my past life to her that she is constantly taunting me to death.