Performing isn't the be all and end all of music and song. I much prefer informal sessions and, to a lesser extent, singarounds. Even playing and singing on one's own can be an enjoyable experience or in other situations where there may be even others present but who are not obliged to listen.

Of course, we still need performers and that could or should (If you really want it) be you. It's very understandable to get these feelings and doubts though especially in the more formal serious singing gatherings, open mics, some floor spots etc. One thing I've noticed, even as a listener, is that many of the other singers etc are so interested in doing their own thing at Open Mics etc that they don't listen to other performers properly. Some really rude ones will even leave after they've done their bit.
This is even happening in some folk clubs these days where the so called "floor spot" has been pre arranged and the artists have little empathy with either the audience or the main act.

However, I agree with most of tbe advice above. If you really want to perform in public, don't give up. Everyone has something to offer although not everyone is necessarily going to appreciate you every time and in every situation. It might be better to be more selective yourself and choose your venues and general performing outlets where you are likely to feel the most comfortable.