Of course, my pleasure - I could feel the pain in your worRAB...
You do want to get control over this, so it does not continue to overflow into your relationship, as you mention. Ask your partner for patience while you work on getting this under control.
It is time for you to allow yourself to take control back from this encounter, that you realize was a mistake with risks. Every day that passes the risk of disease gets lower, therefore everyday that passes, you need to let go of a bit more stress. It only make sense, it neeRAB to be the bottom line.
People have encounters with others by the millions, with a small percentage of them contracting an STD. Of those with STD's, they are able to live happily and healthy with treatment that is easy to obtain. Perhaps you could go to the HIV board and chat with some of those living with STD's. It is not the very worst thing in the world.
That is worse case scenario! Is that worth your health being lost to anxiety, to cause you to not eat, not sleep, have relationship problems? NO!
I am not trying to be hard on you, just trying to point out how to run this thing out of your life. It is something you might have to just do, point blank.
You have nothing to loose here, take your life back from anxiety over something so little.
I wish you well, and I hope I have helped a little. I have won the war against anxiety, or at least how to stop it from taking more than a little spot in my life. You can do this!