If you are following a course, remember that your teacher is there to create a safe environment for you to learn from your mistakes.
Yes, mistakes are good!
Making mistakes is very important because you can see which areas you need to work on. The key is to try not to make the same mistake twice.
No one is there to make fun of you. You can be certain that your teacher is working hard to ensure that you reach your full potential.
Your teacher is also there to celebrate your accomplishments. They want to encourage you to continue practicing, and will tell you what you are doing right.
If you want to feel more comfortable in class, try to get to know your teacher better. It is ok to ask personal questions such as their hobbies or why they decided to become a teacher. If you share information about yourself you will feel more comfortable sharing your frustrations about learning English.