Awww WOS, thats sad, esp about your 2nd sister. I totally agree with gina, just because you're related doesn't mean you have to like or love them. I love my mum and brother but I don't like my brother. I care about my dad but I don't love him, I can't forgive him for what he did in the past. His family were making me ill, so I have had nothing to do with them in nearly 10 years (im only 24) and I feel so much better for it!
I think people would like to believe that all families love each other and are happy together.
I believe in urban families - really close friends who will be there for you no matter what. Blood families can take advantage of the blood tie, and expect you to forgive and forget anything just because you're family, but it shouldn't be this way.
So no, I don't think you're a freak for feeling this way, just honest!