I see. I'm sorry.
It's not easy to break that barrier. Baby steps, even if you don't make it on stage you're still making huge progress. Even if you can't now you still have time in the future. Maybe a year from now you can get on stage. As long as you're moving forward and making progress you can't be blamed for your shortcomings and you shouldn't hate yourself! Only when you've given up and grow stagnant do you deserve to think of yourself that way.
I went hikikomori nuts and never left the house for several years, except when working, and eventually melted down and stopped even working and became this unkempt hermit hiding in a cave. It took time but I have found something closer to normal, but even today I felt like a frightened rodent trying to eat alone at a restaurant with all the people everywhere. Maybe it's not the same but the point is we all make progress.
You can get on stage despite your past eventually. You'll make it.