I'm 13 and Depressed because....?

My parents divorced when I was little. I live with my mom and I miss my dad so much. He said I can stay with him if there's anything bad that ever happens. So I tried to talk to my mom about it and when I told her I wanted to live with him she broke down and cried. I couldn't stand to see my own mom this way so I said I wouldn't stay with him. I told my dad I wasn't gonna live with him and though he wouldn't admit it, I could tell he was hurt. I have a stepdad that's ok, and two stepbrothers, and a sister. My dad has a new wife. At my moms Im always being ordered to do something and I feel like i'm not wanted at my moms at ALL. At my dads I feel wanted and I love being there. But if I went to my dads I know it would DESTROY my moms heart, and now I dont know If I could live with that. Know I've become depressed and have gotten to the point to where I want to run away, just get away from all this. What should I do? :(