My guess is she’s trying to make a few bucks in her old age and this memory is all she has left to sell. What she gets for her story plus $5 will buy her a nice cuppa Joe at Starbucks.
She must have some physical evidence, else literally anyone could claim to be have been a mistress.
What forensic-level proof has she presented? A semen-stained "Blue Dress?"
Of course, my tagline (see below) might not be applicable here. The claim is not all that extraordinary, after all.
Regards,