I have a feeling that this is the core issue that has become the tie that binds the family together. If that is the case, they would probably see you as a threat and close ranks against you. I know it is not fair or right, but in this instance, this denial is a very strong malidaptive coping mechanism. It is an old strong way of keeping the family together...with shame and secrets. Anyone who goes against them will bear the brunt of this. If someone does not go along even if they really are not in denial may choose to go along with their lie so they will not have to go through the pain you are going through. And you know what? You are the perfect example of what will happen to them if they don't at least play along. This means they are projecting their pain onto you. What you need is a really strong support ndtwork of which if you like we can be a part of. But it is important to also have a therapist, a pdoc if needed, support groups and supportive friends. You might also want to google inscest support sites.