Dota isn't really too demanding, my brother can play it on our 2007 iMac at a steady frame rate - his mac only has 256mb video ram! Once you get into dota, you can never get out again.
All I can say, is that you must have a hell of a lot of patience. I can't understand why people would be like that? Also, is your mum taking anger out directly on you? From what I have read it seems like you have been neglected by your mother all your life - it makes me realise how lucky I am. I hop...