I know my group will want me to speak to them, but how do I get the confidence and comfort to speak to them about anything?

There are many ways to help yourself a bit. You can try practising the talk with a mirror or maybe write down everything you want to say. Some people have their own ways of making it easier, not looking directly on people while talking works too. Some people have it easier when they get in proper mood with use of music. Some might want to have something in their hands while speaking, look at it, use it while speaking, let yourself act like you'd be talking to yourself - speaking out loud, not directly to someone. I know a person that feels safer talking difficult matters with her plushies in hands and he actually brought them school at times. Find something that affects you and lets your focus switch.