I would feel quite betrayed if an extremely personal thing like that was told.
It would be adding betrayal of trust on top of the abuse!
It takes a long time to be able to trust, being betrayed like that would set back the growth made in learning to trust people.
It would be a second wave of damage in learning to trust people and have normal relationships,
You have no way of knowing his family won't turn on him. People do strange things when CSA is the topic.
Maybe you wait and watch a little, while maintaining a standard of how he treats you. His past abuse is no excuse for you to be treated poorly now.
It can get better. I used things learned in AA, coming here for a while, and talked with a woman friend in AA to help me. I think I have a decent relationship with my wife
. Lasted a long time.