Why is my 11yr old daughter is so angry?

My 11yr old daughter is lazy and angry when I tell her something I tell her clean up the house, or pick up the toys or even look after her little brothers she gives me a filthy look and sighs and I send her to her room. I have deleted minecraft and battlefield 3 and she got minecraft back I accepted that she could have it back. In the daylight she'll play 3DS,PSP VITA and won't socialise for an hour. She evens hits her 3yr old brother!

I really love her she has cerbral palsy which cause brain damage and couldn't walk until she was 4yrs old but she's becoming a spoilt girl. What do I do with her?

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