Hi GaGagirl,
I like your name! Your English is fine, no worries.
I am sorry you are having a difficult time in regard to your sister. I am thinking of you and I'm glad you joined us. Please stick around and check out the forums. We are here for you!
My boyfriend's son has autism. He is a wonderful boy and I love him. My boyfriend also has a daughter who is "normal" and I love her, too. I see both of his two kids as equals and not one being better than the other. In fact, I may slightly favor his son not because I feel sorry for him but because, well, I like his personality and connect with him even though he is not very talkative.
Welcome to PC!