Should you tell the partner of someone that you were a mistress to their partner?

No dwelling on the past. Old news! Today is a new day.

No, you should not tell someone that you were a mistress to their partner.

ANSWER:

I'm not sure if this relationship is over because of the word " were", don't get me wrong, in my opinion only 2 way why you want to tell to a complete stranger, who you are or were, because the man stop and went back to her and you didn't like it. Or your feeling guilty and you want to stop but he don't. Either way, this will be your decision how to do the right thing. ..