Bounce, I've got to bounce (I know that was corny!) but I wanted to respond before I left.
I do feel that I have to love my mom, even though she's hurt me, and my siblings, a lot. I haven't called on her because I don't love her. I think that because I grew up with all these secrets and lies surrounding anything that wasn't stellar behavior, I hate secrets and lies. Everything should be out in the open, and then people can start healing.
So, I actually think it is a disservice to the person we think we're "protecting" when we don't tell, because it enables them to continue the behavior, and it teaches them to lie, cover up things, not have consequences for their actions, etc.
Also, in the case of a violent crime, I wouldn't be able to live with the other family being so destroyed with not knowing just so my family could stay miserable in secret. I think the family affected deserves the truth more than my family member deserves to keep his/her secret.
Anyway, these are all my opinions based on years in a crazy family
Whatever you can do to keep them away from you is worth a shot (I'm JUST KIDDING!)