Why do I freeze when I dance in front of people?

The freeze is real and it is not a flaw in your character. When a crowd is watching, your body reads it as danger and locks up. That is an old survival wiring, not proof that you cannot dance. You already can dance. The audience just short-circuits it. What helps is shrinking the audience in your mind. You are not performing for a wall of faces. You are performing for the movement itself, and maybe one kind face out there. The eyes feel like judgment, but most of them are simply hoping you do well. People want to enjoy you, not catch you failing. Start smaller than the big stage. Dance in front of one trusted person, then two, then a small room. Let your body learn that being watched does not end in harm. The freeze loosens with repetition, not with willpower. Give it reps and it will fade.