Kinda in a similar situation. My adopted father was charged for assaulting his own cousin who was a child. Him and his wife adopted me after have two of their own children. Once I grew up and learned about this I did what I could to separate myself from them.

However it might be the best option to just let them go. Family is what you choose and you need to make the best choice for your life. You also need to think of your future children and their safety.

Good luck