You can pick your friends but you cant choose your family?

The pot has been stirred, bubbling, boiling and overflowed. The feud has begun between my parents and my sister. I had my outburst christmas day 2004 and, i havnt seen her since or spoken.
Her and i are two totally DIFFERENT people. No matter how hard i try and mend the differences, put in the effort to have a sister and be close, nothing comes to fruition. She has had hard times in the past battling severe depression, including post natal depresion. We ( mum , dad and i) have been there for her and assisted where necessary. She for some reason walks over the family. "Others have always come first," not her own flesh and blood.
My father is ropable at the present time with her behaviour. She thinks there is a reason for the way she is and is looking for answers. Her search is leaning toward her upbringing. I know for a fact that my parents worked hard to provide disclipline, good education, entertainment(family outings), and holidys. I cant fault them! I too have run into trouble in the past. And guess who were there for me for support and for a time in need? My wonderful loving parents.No one is perfect in this world. Not even me. But give me a break! When your depresed and down in the dumps, why ignore your family and treat them like shit! well, even if your not depressed why portray this behaviour?
I remember clear as daylight when her son was being christened, she ignored me, my mother and father. Not even a hello or a goodbye.That upset me. I recall being in tears. I presume my parents feelings were hurt that day.
There is sooo much i could include in my blog entry, but i wont as this will end up being a bulky novel!
On discussion recently with my father, he told me that he was treated like shit at her wedding. He hasnt forgotten that. I cant comment as i did not attend(thats another story). Now this is what i suppose that disturbed me. what he then said about his eldest daughter."I lost a daughter years ago." I was shocked to hear this, but on the other hand it didnt surprise me. To hear my own father say this to my face made me realise the pain and suffering that my sister has caused.
I was a little weary about writing this as its a very personal topic. However, i wanted to get it off my chest as im feeling a little sad. Right now im thinking of how jelous i feel when i hear of friends telling me about outings or visits with their brothers or sisters. I have never had that. well, maybe once or twice. In the two years that i have been living in this house she has been here once. And when i lived in a unit by myself for 18 months, threre was not one visit. Its always been me going out of my way to travel 40 minutes one way to her house!
ARGH. I better stop now as im getting worked up.......
One thing i have to say is that i Love my "surrogate sister," you know who you are. And i mean what i write.