This patient support community is for discussions relating to relationships, abstinence, arousal problems, birth control, cohabitation, commitment, communication, couples counseling, desire, sexual technique, and sexually transmitted diseases (STDs).
If everyone is okay with finding out about this, then go for it. It will give all of you closure, and you can move on with your lives from there, wherever they may lead.
If they both want nothing to do with you now, then accept the fact that you were a selfish jerk, she may have been a selfish jerk as well, you made a mistake and didn't take responsibility for finding out if you needed to remain involved, and let it go. At least then you will know, 20 years after, that you finally stepped up to the plate to take responsibilities for your actions.
What is the second half of the story? How does it relate to what you have already written?