Getting on stage with the difficulty of managing your emotions take away the joy of playing.
Playing without emotion (submerging) does not mean playing without musicality.
Develop your physical landmarks, those that anchor and stabilize you.
Mismanagement of emotions limits technical abilities and expression.
You limit your endurance and that is exactly what is stressing you.
So you have the choice to go on stage calmly, staying connected with your feelings or get lost in your emotions, it is one or the other.
Also, respiration is often used to manage emotions.
But, while you play music, a too low respiration (abdominal or deep or ventral or diaphragmatic) does not relax you.
Indeed, a ventral respiration makes the abdominals malfunction, tires the back muscles, the shoulders, or the lips.
These technical consequences quickly become very anxiety-provoking.
The “calm” allows to gather all the necessary technical elements to play.
A tonic PHYSIC and a relaxed MENTAL = Joy of Playing