One of the few advantages of getting older is, usually, that you don't give a f what other people think about you. I generally don't.
Sounds like your friend was just joking and you've taken it the wrong way. Of course we don't know just how enthusiastically you were singing. Did you stand up in front of the crowd thinking you sounded like one of the three tenors , when in fact you sounded more like one of the three stooges or was it a more restrained performance.