If alcohol is causing a problem with his anger then he may be masking some of his true feelings with the alcohol. And me, being an alcoholic, hid so many feelings with alcohol it all bottlenecked and overwhelmed me. I'm not saying he has a problem and you wont be able to help him unless he wants the help, but he definetly needs to know how you TRULY feel about it.
ohh and Welcome to SR!!
much love
Justin