God, why can't she love me?

My mother has told us plain out she hates us. I wasn't supposed to be born and neither was my brother. She tried to get an abortion with us both, but my dad wouldn't let her. My parents were in a forced marriage and they don't love each other. My mom won't let me see my half brother and says that in her eyes, he doesn't exist. She took a day job so in her own words, "I don't have to put up with you alls ****." And now she makes me do all the chores and I've become more of a mother to my younger brother than she has ever been. My mother has never taken me anywhere and I haven't has a birthday party since I was three and I see my mother about an hour every day. At one point she even stopped talking to me for a month because my sister said it was my fault the whole family was screwed up. I try not to do anything wrong, but I'm a teenager... Ever since I was born my parents have abused me and it's just now starting to stop. She still says she hates me, though, and says that we were mistakes. Why can't she just love me and give me the unconditional love a mother is suppose to give? When I asked my dad to take me to a therapist and start having me put on antidepressants, they told him he needed her signed consent. However, she told him she wouldn't because she didn't want anyone to know all that goes on here. And in his words, "She doesn't want them to know how bad of a mother she is." Yet for some reason, he still won't get a divorce. So can anyone tell me, why is it that she doesn't love me? And no, I'm not being a drama queen. It is seriously like this and worse.