I hope you found the courage to go in today. When really bad you can always ask a friend to introduce you. Potentially inform the lecturer that you are finding this very difficult. Many will provide some help in these situations. I know the pain of group introductions. At the same time, once it is done it is done. If you missed it you won’t know peoples names, you miss a shared experience, it will be harder to connect to people and at some point you will likely have to do it anyway. Good luck mate.