The feeling of "we don't talk about it" is generational. My grandparents never talked about anything.."Children should be seen and not heard" was the way they were raised. Our parents were a tad more open...but still buy into that belief.
I believe most folks cannot fathom the CSA as a subject in itself, let alone having it occur with someone so close or even harder, someone they love.
Certain professionals (Cops, Firefighters, Doctors, Medical personnel) seem to be taught " no discuss/no disclose" as part of their professions way of dealing with the atrocities they see daily. I can't help but think that it crosses into their private lives too.
As I previously said, give them a chance to know you (not just the CSA) and you'll get to know them and see if you truly wish to forge a friendship.
Give yourself a break Coop.
You're a great man and they love you,
they just need to come to terms with it all.
May I suggest, if they are open to it, a book or article about CSA. Something simply written, that would give them a better understanding.
With knowledge comes understanding and acceptance.
God will guide them as he does us all.