I feel so bad for you that that old memory is still stuck and is still tormenting you. I have some of those types of memories. Maybe we all do, I don't know.
What's an elliptical?
There's no getting around the fact that the incident with the woman and her son and daughter has triggered that memory for you. I haven't gone back to read through this thread and I don't recall - have you spoken with a therapist about your memory? I was having dreams almost every single night about an incident from my past. The dreams were disturbing me terribly. I didn't believe that there was any way to rid myself of the memory those dreams were repeatedly reminding me of. Then one day I wrote out the story of the entire memory, took what I'd written to a therapy session and read the whole thing to my therapist.
That was 5 weeks ago. I have not had the dream once since that therapy session. Not one time. I'm quite shocked - I certainly didn't believe that writing that memory down and reading it to my therapist would help one bit. But, go figure. What a relief!