Why doesn't my mom like me?

About a year and a half ago, so lady named Whimpy became friends with my mom. Whimpy introduced my mom to dating, and ever since me and my have been fighting. Im a 13 year old boy, who is 6 foot 2, and 180 pounds. My mom is 5 foot 7 and 220 pounds. She always calls me fat, and tells me she never wanted a 3rd child. Today she told me she wasn't proud of me, she said if I was half the child as my oldest brother was, she would be proud of me. She tells me she wants me to live with my dad, and that she hates me, and she can't stand to look at me. I don't know why she isn't proud of me, Im a A honor roll student, a football player, and Im the youngest boy in my family but Im the only one with a job. I also lost 15 pounds just a little bit ago, and she never said good job, she just called me fat. She doesn't trust me with money, she thinks ill steal it. But, I would never do that. Stealing's a sin. I always argue with her, because she dates men, I don't like it. She wants me to be like all the other children, my 2 brothers, and my sister. Because, they don't mind her dating, the reason I do is Im the only one that cares. The others don't they only care about getting what they want. There just spoiled and lazy. She always accuses me of things, but why?