Hi
I had also read lots of horror stories and was absolutely dreading my HSG, I was feeling sick at the thought of it and almost called it off at the last minute cos I was so terrified! In the end it was totally fine. The speculum thing going in is never pleasant but that was just the same as a smear test, actually it was in for less time than during a smear test. I didn't feel anything at all when the dye was going in, and the whole thing was over in about 10 minutes maximum. I had a few light period-type cramps for a few hours afterwards, but they were no problem. I took a couple of nurofen about 20-30 mins before. I am sure that you will be fine, just try to relax. I just tried to chat to the nurse about her holidays in order to distract me whilst the doctor was doing her thing..
Good luck!
Px