you know it will be OK, and you know you have to do it... deep breaths, a few mega squirts of rescue remedy.. and call the dentist and tell him you are bottling out, get him to give you a couple of Valiums for the night before and the morning of...
Tell the dentist that you are scared of needles, scared of the injection and scared of feeling pain, so ask him to give you a full dose of the anaesthetic (sp?).
How about taking some teething gel, and rubbing your gums with it so you don't feel the needle going in?
It'll be OK, i know exactly what you are feeling, have had a stack of stuff done too, was FINE, got really used to it all.. One horrific operation and I ended up going home and literally passing out with post traumatic shock...
When I got back to the UK, one of my teeth fell apart and it had to come out, i was beside myself, but I really couldn't take the pain any more.
Don't let it get to that, you can do it, we're all rooting for you! (no pun intended!!)
So no, YANBU to feel like you do, but it would be an unreasonable thing to do to yourself, to give in and leave it. Good luck!