Reporting abuse in my friend’s house?

What I saw when I went to my freind’s house un announced shocked me. I saw the husband hit my friend several times in the eye; I saw emotional abuse; I saw meth on the table.

I know he has been abused for awhile – or at least what it looks like. My question is do I have to have him go with me to give a statement, backing up what he’s going through, or can I single-handedly report him for abuse?

(for all other questions… see my last question for details on what happened)