It may be easier for your husband if he writes a letter to the perp uncle stating how he feels and how the abuse has affected his life. Encourage him to write it with no intention of ever sending it; the letter is just a vehicle for him to express how he feels.
He may feel more comfortable doing that than writing down things specifically for use in court, and then he can look at his letter and see what he can take from it to report to the court. But he is the only one who really knows his feelings and it's important that he acknowledge and "own" those feelings.
Nobody living can ever stop me
As I go walking my freedom highway.
Nobody living can make me turn back:
This land was made for you and me. (Woody Guthrie)