I don't know how much this will help you but I have sort of a similar story. It's not related to csa, but it does concern a "friend" who didn't know how to comfort/support me.

My dad died 13 years ago, when I was 22. The details are still hard to talk about sometimes, but I will say that it was somewhat sudden and I didn't get to tell him goodbye. Y best friend, whom I had known since the 7th grade told me to call her whenever I needed her. I said ok. I never called her and she never called me. Just like that. We eventually became friends again and she told me that she just didn't know how to deal with it, she knew my dad and was struggling with his death, etc. I eventually forgave her, but I never rely on her for the hard stuff. She's no good at it. Perhaps your friend has this same issue. I'm not defending him in any way, it's just a theory I wanted to throw out there. Either way, you deserve a better friend than that.