Welcome back ladies and gentlemen of the internet. When you marry someone, you expect that all secrets will be put out in the open. Of course, if we have shameful things in our past we may not be so inclined to open up about those things. In my opinion, it's better to get everything out to each other, not only to heal from the past, but to create transparency and intimacy between the couple. If the person truly loves you, they will accept you for your past mistakes, barring that they know you've changed.
This brings us to the Reddit thread. In this story, the original poster (OP) is a woman whose past has been sullied by the infidelity of others. Though she's broken from her painful wounds and found a new life and new husband, her past comes back to the forefront of her life. Despite moving far away, she meets the 'other woman' who ended her engagement. She tries not to get into the thick of it, but the woman's husband demands to know the truth.