Whatever you decide to do, leave yourself an out, a trapdoor to escape through. If the conversation begins to incite too much negative reaction,( too much is your call), have a scripted, calculated path away from the fire. Proceed with extreme caution; all available wits about you and in the safest, most relaxed atmosphere you can construct. Purposeful exclusion, premeditated, of any possible entry into a situation which could breed animosity between you and family members, (who are ignorant of the truth you're going to hit them with) is in everyone's best interest. Don't do it to get even with or punish the perpetrator. You don't want to run the risk of coming off as the bad guy. In the end you're fall back position is-as you address-honest, unvarnished truth is best for all. Sometimes it's only possible after so many years have passed. Both of my parents were abused and carry scars so deep they were never able to fully function as whole human beings. My mother did rise above it by turning to her spiritual strength and helping others. My father is a mean, angry, bitter, lonely man-he never had a chance to confront the truth with someone who believed or understood. He and I(his eldest son) didn't speak about it at all until I was over 50, now he's 83.