I guess we for got he's black..

A group of us were together last night at a party. One of us is a black man. A good friend to all present. Well, after a few drinks, one of us tells a really bad racial joke that included the "N" word. We all laughed, completely forgetting our black friend being present. Without saying a word the guy left. Needless to say the party then ended. All of us felt like shit. Now our black friend won't answer anyone's voice mails. Won't take any of our calls. Won't even answer his doorbell. Each of us has tried to see him to say how sorry we all are. Is it normal for a person to be so well liked that he blends in with a group of people so much that we forget what color he is? It sucks to lose a friend this way. Because I laughed too, I feel just as guilty as the one who told that awful racist joke.