sounds like a REALLY tough situation.
I cant say my relationship with my family is great, but nothing like that. I have chosen to limit my dd's contact with my family, not because of any issues over my lifestyle, (they're not "happy" about it, but they accept me because that's who I am and I'm happy) but because when someone in our family came out and admitted that she'd been sexually abused by another family member, the whole family accused the young girl of lying and took the side of my grandfather, and refused to talk about it.
I choose to distance myself, and my daughter, from people who act like this. For me its not so hard, as we live in another country now. But I made that choice after a lot of suffering and soul-searching.
If my family ever show that they are open and willing to change, willing to talk about what happened and to show to my grandfather that what he did was wrong and unacceptable, and to show some support and love to the abused child (now grown-up), then perhaps I would be willing to mend those bridges. but for now, we dont visit, we have very little contact. My grandfather's mail is returned unanswered.
I dont know if this helps at all, and I know it's not exactly the same situation, but there is a point where you can see that a situation is unhealthy, and it's not up to you to heal or change anyone else but yourself. So sometimes it happens that the best thing is just to remove ourselves from an unhealthy situation. It's NOT "running away", it's putting a healthy distance between yourself (and your child) and a potentially damaging situation.
All the best, let us know how it works out for you. Perhaps someone else will have some more advice and ideas for you...