Don't worry Meat, it wouldn't matter if you couldn't sing at all: all you have to do is walk on stage and I'd be happy :P . I know how frustrating it is to have a less-than-100% voice when you love to perform so much. Don't let it get your spirits down though, I don't think any Meat Loaf fan would give up their ticket because of it!
Happy Birthday
BillyBoy