Yes, it's really scary. Yes, you get nervous. Yes, you worry about the worst case scenario. Even with all of that, you have to go for it. Let's forget music for a second and think about how we deal with this in life. Honestly, I'm usually a very shy and introverted person, but when I'm with someone I know I open up immediately. I'm not advocating just going out and befriending or trusting everyone, but at some level, if you are completely shut off from people, physically, socially, etc., nothing new can come of your interactions; sometimes they never take place! I think the main reason for these feelings of uncertainty and hesitation in our lives is the perception of stakes or risks.
When you have a long time friend, maybe after a while, you might start feeling those butterflies in your stomach. I know that's happened to me a couple of times, and I immediately got nervous because I don't want to jeopardize the friendship in any way; so I hesitated. Or when you were a child in elementary school and wanted to make friends, but you might've worried that they wouldn't accept or like you. Even as adults we experience that, but as nervous as we may get, if we give into that feeling we deny ourselves the opportunities that arise, then nothing gets done, nothing progresses, and you never know what could've been. Of course things are "on the line," but our view of it really is not as high stakes as we make it out to be.
I've accepted the fact that rejection is an option, and if it does happen, it's better than not knowing at all. The good thing about real friends is that they're honest and obviously care about you, so they won't be trying to hurt you. Honestly, when I did go for it, it felt like I was in an audition again and thought, "I hope I don't mess up, I hope they like me, I hope I get my points across," but If I never tried, they wouldn't have known and I wouldn't have known. You have to get out of that comfort zone and allow yourself to both be you and to let them see you! If they don't see what you can do and who you are as a person/musician, they won't have the motivation to advance/hire you, or to date you. So yeah, it's really scary to put yourself out there, but it's very necessary in our lives.
It's nice to start small with this and to take baby steps towards opening up and going for things, and it makes it easier in the practice room when you practice this in your life. Ask a person out, do something you've wanted to do for years, talk to a close friend about things you're passionate about or things you really can't stand, anything that you think has risks. Know that it's not the end of the world, even though it often feels like it, if you get rejected or if it doesn't pan out the way you wanted. It's better that it happen now than later, and it opens up new opportunities for the future either way. If it doesn't work out now, there's always next time. You'll have another chance at an audition, a date, a relationship, a job, an interview, achieving a goal, etc. We obviously want things to work out, but we have to be ok with the chance that it might not. So go for it now and don't let fear or uncertainty stop you from acting on your feelings, dreams or desires in life (or in the audition).