My mom is so mean to me and treats my sister like a god. Why?

I can relate. My family dynamics were the same. Your mom might not realize what she is doing. Have you tried writing a letter to het expressing your feelings?

It could be many reasons behind this. I understand what you are going through since I have been through that as well. It could be favoritism. However don't make this pull you down. Remember you both are equal in every way. Your mother's preferences doesn't change the fact that you are both human. Even though your mother may be mean try to think positive about the present and the future. Don't let her words affect you and your self esteem. Even though she may not be the most affectionate right now that doesn't mean she can't change in the future. Keep fighting!