POV you find your girl is talking to her ex bf. What do you do/say?

It's over

Do u know what are they talking about? 👀 I have seen some are okay with that as long as it is just casual talk, some are not at all okay with it so depends on each individual.
If it bothers you, You can ask why are they continuing to talk post break up? (be calm when u speak first)
Make your girl understand that u get bothered with it
Ask her if she can introduce him to you (if she tells it’s just friendship now).

As a personal opinion, I would want the past to be buried so that we can focus on the future better.