Why do families sweep conflicts under the rug?

About 2 years ago my 2 older sisters decided to cut me and my other sister out of their lives. Since then my family has regarded it as a deep dark secret or a taboo subject. Even my mother refuses to talk about the situation even though it has really effected me and my sister negatively and I have developed depression and am seeing a counsellor because of it. I feel like I'm being ostracized from my family and I can't ever bring up the subject to defend my side of the argument. I don't understand why my family feels like they have to sweep this situation under the rug. It's almost like they would rather avoid conflict than deal with a real situation that desperately needs fixing. Has anyone else experienced families acting like this? Auntes, Uncles, Parents, Grandparents, Siblings, Cousins??? Have they chosen to ignorance over you and your well being?