Really glad you posted! It's good to see at least he can talk about the abuse (so many can't.) I firmly believe (from experience!) that this is truly the starting point of healing from it. Loved ones often confuse things like alcohol abuse as problems instead of symptoms of a problem. I think that's where you are on the right track and his other loved ones are perhaps incorrect.
He drinks BECAUSE he has a need for something (perhaps escape, numbing disturbing feelings, and so on) and not just because it tastes good. It stands to reason that, once the reasons are eliminated (through dealing with the csa and not being in its grasp,) the drinking should disappear or at least become manageable. At least that's been my experience. I went from nearly a bottle of wine per day
to around 1-2 glasses of wine per month, and I honestly don't miss it.
Even though he's seen a few therapists, I know how tricky that can be. I had several misfires before I found the one I see now, and she's absolutely wonderful. I'm hoping he will keep looking until he crosses paths with the right one.
Finally, bless you for being so supportive of him!
Don't be afraid to be sort of a "broken record." Keep letting him know that you're here to talk about it and don't be concerned if he gets emotional. Holding them in is bad; letting them out is good.
As long as he doesn't get violent, it's all good. You won't harm him emotionally; the damage has already been done. Gently suggesting that you're available (but leaving the control of talking about it in his hands) won't cause him any additional trauma. If anything, it could nudge him into dealing with it rather than trying to dodge it any longer through drinking, etc.
Sam's suggestion is good, in my opinion-- consider leaving the computer up, logged on to this site. He'll find an amazing amount of help here when he's ready.
Best to you.