Yes, yes, yes!!! It gets easier every time you do it. And there are few psychological tricks to help you along. Think to yourself, what is really going to happen if I mess up? The answer is nothing. In most cases people will empathize and it would have to be a very rude person indeed to insult or criticize you - therefore their opinion has little value. There will be plenty of people who will encourage you and like what you do. I assume you are singing on an informal basis and not getting paid, but even people doing paid gigs have an off night, make a mistake, start out in the wrong key sometimes, etc. None of these mistakes have horrendous consequences. If you enjoy your singing and your songs, chances are others will too. So force yourself to perform and the nervousness WILL go away.