This seems like a question from a very young person. I'm going to assume that, though it makes this question off topic here. I hope my exception won't be objected to by other users.
Yes, you can talk about this with your teacher and between you a solution might be found, though an obvious move might make your friends also distrust you. I'd suggest not naming people.
But the bigger issue is your shyness. The fact that you are willing to help people is a really good thing. I hope you aren't being coerced into its, though.
The reason I'm giving an answer is to suggest that it is time for you to learn how to overcome your shyness so that you can take a more active role in lots of situations, not only this one.
I, too, was too (far too) shy growing up. It seemed impossible for me to speak up for myself when it was necessary. It was only a lot later that I learned that being shy (introverted) doesn't limit what you can do if you learn to do it. It takes practice, however and maybe a few sessions with a counsellor who can give you tips.
I was once so shy that I couldn't look into people's eyes, though that isn't frowned on in my culture as it is in some. It seemed to me like people could see my soul if I looked directly at them. A counsellor suggested otherwise and I practiced doing what others do naturally and finally overcame it. But, not speaking up in a particular case once caused me a very large setback in my education and career.
I once asked a friend I'd known for a long time if it seemed to him like I'd changed my personality over the years, going from introvert, hiding in the background, to extrovert, putting my ideas out into the general mix. He thought for a moment and decided that yes, so it seemed. I was still the same person inside but seemed to be different outside. An act of a sort, but it becomes easy once you practice it enough.
I have another friend who is very important (famous) in our field (CS) and he is well sought after as a public speaker. But he is actually a bit autistic, which is beyond introverted (not the same, really, but it has similar tendencies for some). He taught himself to act in public by joining an acting group so that he could play roles that hid his personality but let him seem to be as extroverted as necessary in any given situation. He is still quiet, but speaks with authority.
So, it isn't that you can't do certain things. It is that they are uncomfortable for you and you don't, yet, have enough practice in doing so. It can be learned through practice, just like learning math can be.
If you can learn to do such things at an early age and combine it with a willingness to help people learn, you'd probably make an excellent professor someday. It was something I needed to do along my own path, which is what leads me to write this.
It won't surprise me if many users here have something similar in their backgrounds.
Note that the "setback" to my education and career that I describe here happened in grad school, so the need to overcome shyness can hit at any age. Maybe this isn't quite so off topic after all.