Stage fright is common and affects the matter of singing a lot. If we are afraid we are immediately dry throat (not allowing ourselves to sing correctly and even reaching our vocal chords damaged by friction) and produce a lock on the vocal cords, because it puts us neck tense.
This is quite common so we will give you some advice and some exercises to controls your dread. The exercise is simple, consists of a deep breath, filling your lungs completely, and then releasing all the air slowly. We do this about ten times.
Then we repeat the exercise again taking a deep breath, always slowly, and releasing it slowly, but this time blowing blows, as if we were fu fu, fu (It is difficult to explain without making a face), this second 10 other times we do.
After the exercises you have to leave thinking that is going to leave all well, dominate what sing and the vast majority of the people that is going to see you, does not understand of song neither they know to sing for which when they listen someone that knows to sing, however little know, they are going to know to appreciate it.
You have mastered your voice on these issues that are going to sing and all that is tested and crushed in the end pays off and goes as it should (Leaving aside that was never satisfied to 100% but that does not mean that has gone well).
We expect that the exercises they serve you, they are very simple but they function truly, and if with 10 and 10 not sufficient tennis you do 15 and 15 and a little but fast.