An, please don't let Guest Ray spook you (or Guest Les B, for that matter).

From what you've told us, you are not "obviously" tone-deaf (and I would say that's a very rare condition, and has not been defined scientifically).

I agree that it may be useful to see a professional voice trainer and ask their opinion of your ability. Not being a friend, s/he would be able to give an unbiased assessment.

Cheers,
Michael