Oh my goodness! I would never even think someone would do that! how shady and sneaky!! I would agree that hiring a computer geek to try and retreive the pictures is your best bet to save you =/ before you have them come out though, ask them if there is any way they can help...no need to waste money if all the messages are gone. Also check your trash box...
I'm sure you probably did that already but that is my suggestions! keep us posted and good luck!