How should I approach this?

So…my fiance’s ex wife and he “hate” each other but they both have each other’s family’s and themselves on FB. They talk often and always through FB messanger…they are terrible at getting along and do not co parent, or even attempt. Is it wrong of me to be annoyed that he refuses to get rid of her on FB and uses it to look at her photos and all? I think it’s bullshit and I’m pretty much over it. How would y’all approach this situation and conversation?