Dealing with a step mom "that hates me"

I can't stand my step mom because she is always trying to get my dads attention and I have to fight for it. It makes me so mad and now I am in a group home because of her and know she won't let me see my little baby brother and she won't allow me to come back there and live there. I have tried to be the big person and wrote her a letter and she didn't even write back and I got her and my brother a Christmas present and she wouldn't open hers and she wouldn't let my little baby brother open his. My dad kept the one for my brother and he is going to give it to him, but he gave the two I got for her back to me. I don't know what to do
Please help me

Destinie