I understood the situations to be like this:
You have a boyfriend and you saw him kissing his ex-girlfriend, right? And you are asking what to do?
This is not about dealing with the past. This is very much the present
There's nothing to debate here. Say good-bye and move on with your life.
If your boyfriend kisses another girl, against the norms of your relationship (could be [polyamory] (https://steemit.com/advice/@nomad-magus/i-fancy-a-guy-that-i-met-have-i-stopped-loving-my-boyfriend-some-words-about-polyamory), then he clearly made the choice: "I don't want to be with you; I am choosing another one".
you are right.this is not about dealing with the past. i continue my present. forget my past. i visit your link & read the advice. its too good. now i am feeling better.
yes i told my past, i forget you & now i move on my life.