That is a very good question. I only stumbled across the info when I was looking up something else in canon law. How many ordinary people thumb through canon law? It doesn't seem to have been thought through very well, but I guess I wouldn't expect any priest to mirandize me in the process of making a confession.
I hate to be the bearer of bad tidings, but since you now know, you are obligated to seek out a confessor and follow his advice, if you haven't already done so, or you *may* be excommunicated. Not that *I* consider you excommunicated. They will probably just blow it off and tell you to get on with things.
I don't know why it struck me with such terror. I do not think most people would react that way.
That was a long time ago. You were a good girl. He was a naughty priest, but all too human. It probably happens more than we know.
Why, do I have to now? It's been superceded by the 1983 Code of Canon law, has it not? And I did not find about this secret rule until 2003.