How to proceed. Friend hit his (ex)girlfriend, anger involved, although she said she got him to the tipping point....more inside

A little more, theyve been fighting. they always fight, like usual couples. anyway, i guess he got really mad (recently hes been weary, breaking down, going lower it seems) i dont know if alcohol was involved, probable. She said she got him to the tipping point, so its not entirely his fault, however i know you must never resort to violence. Now since im in the middle, she wants me to get help for his anger issues. I cant really say anything about him being angry, because we never talk about that stuff when we see each other. I guess we talk about better stuff, he laughs a lot. Ive really never seen him angry personally. What do I do. She wants me to help. How can I even begin to tell him you have problems when Ive never seen him like that? How can you even get someone to go? I dont think she wants to press charges, theyve been together a long time. first time anything like this ever happen. sigh. fuckin sucks. i dont have all the details of course, been trying to sit on it and just think. I could use some thoughts.