favouritism

Obeying one's mother

Q: I am passing through a bad phase in life. My mother shows favoratisam between her children. She always hates so in return I disobey her. She prefers my brothers, what should I do in these circumstances? I want to commit suicide. She looks down upon me and teases me. I am an aalima and 25 years old. I feel a block on my heart when I disobey her but what can I do? Am I a sinner? How can I obey her?