For me, the feeling of shame of talking to people and the behavior of therefore avoiding people because of that shame reinforced itself. By that, I mean that it's a cycle, in which the feeling of shame and the behavior of avoiding people reinforce each other.
To get out of that cycle, I feel like I had success just hijacking that cycle, if you will. For me, I think if I just tried to talk to people more it would sometimes help get rid of that feeling. Or if I was really intentional about it--the act of talking to others. I would come in and ask particular questions and try to be really present with another person. Those are some things that helped me.