Hi there. Your post isn't much to go off of. There is a reality where you aren't there yet and need to grow more before you join the ministry. There's also a reality where you are good, but don't fit stylistically. Sometimes people can be harsh even in that case.
I would say take an honest look at where you are now, and the expectation the ministry has for musicians and work on any problem spots you can find. If you find that you are too biased for or against yourself, record yourself and ask some who will tell you the truth in love what they think.
Being told you're not very good is never pleasant, but if it only hit you hard cause a preacher said it, then it's likely that you have that preacher on a pedestal in your mind. If this is true, you'll need to work on fixing how you think of this guy.
If it hurt because he conveyed his opinion in a mean way, then he needs to work on how he talks to people. Also, I'd say you need to work on (*sigh* cliche incoming) encouraging yourself. In situations where I know I need to grow, but someone was mean about it, I find it helpful to tell myself something along the lines of, "I'm not all bad. I have some things to work on, but I'm making progress. I'm growing." Zech 4:10 is an encouragement to me when I find myself being hard on myself for not being farther along in a new skill.
I hope this helps.
