What should I do?

So, my son has been invited over to my brother's place for some fishing over the weekend, but here's the thing: he's been accused multiple times of child molestation. I don't believe the claims that have been thrown at him, but when he was offering the visit to me, he said things like, "Maybe I'll fuck his ass a little," then proceeding to laugh, and saying, "Inside joke." It made me more uneasy if I should accept or not. He's my brother, so I want to trust him! Please give me some advice.