Ah yes, I would imagine it likely that Sharon will overhear Phil/Shirley, like you said, I can't see that Shirley would reveal it with the risk of Phil telling Mick, though what happened to him blackmailing her for the money? I think i missed the conclusion of that.
Sharon is the victim, Phil is guilty and Shirley isn't happy about what he has done either so this isn't going to bode well for Phil, I hope. Haha. I hear that Sharon's attack s/l comes to a head in Autumn so perhaps something happens then?