How do you know when you need to tell those around you?

When I was 7 my sister that was 18 married a guy that I adored. He was the big brother that I always wanted. When I was 12 or 13 he started making comments about the changes that were happening to my body. I didn't think too much about it but it continued and after my sister had their third child he persuaded me to perform oral sex on him. I felt that is was wrong but I trusted him because he was "my big brother" and only wanted the best for me, right? That happened a few more times before he tried to have intercourse with me. I don't know why he stopped but he did and I remember him saying that he stopped because he didn't want to hurt me...but that had already happened. My life has seemed to go pretty smooth considering this and the fact that my mother is bipolar and my dad was an alcoholic growing up. I have realized recently that this may not have happened to me if I hadn't had such low self esteem and not been having problems at home. I think he saw this in me and used it to his advantage. The ways he acts and talks about women you'd think that most people would pick up on all the "red flags", my husband wasn't shocked when I told him about the things that had happened. I am now wondering if I should confront him and the rest of my family and tell them everything. I have a friend that I have shared this information with and she is determined that I should...what if it has happened to someone else? Isn't my fault if I don't come forth with my information?