Yeah, that's where the story is kinda falling appart, because at this point the only explanation is that Emily is either a fuckin idiot, or an evil asshole who wants to see the world burn.
The "back in town" thing tho, that's not completely stupid, because we know Navarro travels a lot, and maybe for extended periods too, because of his job... but yeah, the rest is very puzzling. SPECIALLY when you're on Alexis' path and Emily knows you're banging her... at least with Layla she doesn't seem to be aware of the relationship yet.