Race Fight at Work (Expletive Language)

Yesterday my husband got into a confrontation with a co-worker of his. My husband apparently called out his co-worker on some b.s. (i don't know details of original disagreement). Anyway, things apparently got heated and the co-worker retaliated to my husband: "Fuck you and your nigger wife." So, obviously, yes, I'm black; my husband is white. The rude comment does bother me (but unfortunately I'm used to racial comments), but it's really getting to my husband. My husband won't even talk to me about anything because he's mad at what happened to work. My husband will barely talk to me! What gives?! I advised my husband to accelerate the issue higher up through his HR if it's really bothering him. I don't know if he will, but I'm struggling with his complete silence with me. Is he ashamed of me? How do I proceed from here? How do I console him when he wont even talk to me?