Hi Libby
First let me assure you that you did make a mistake. The good news is - there is no quilting technique that requires physical injury. I don't personally use interfacing very often, but I have found that ironing a length of freezer paper (shiny side down) to the ironing board before I start fusing is an easy way to protect my ironing board cover.
Take a look at make it love it.com. Good pics and lots of info about why you would choose one interfacing over another.
Btw - great colors on your avatar - color choice is all important for quilters
Lefty - in Philly