yeah, it's a shame that you have to think that you were the source of someone's pain, especially if they were kind enough to laugh it off. I have tried to find multiple people that I have wronged in the past and some of them, like the woman in your story likely is, were no longer alive.
I guess the best thing we can do is try to learn from it and not repeat the mistakes in the future.
For sure.. That's all you can really do!