Do I have a case against verizon wireless if one of their employees has been spying on my phone records?

Yes, Verizon is responsible for the misconduct of its employees in the course of their employment when the particular type of misconduct is reasonably foreseeable.  An employee misusing access to phone records is certainly reasonably foreseeable.  Assuming this is only your account (not your ex-husband's or the girlfriends) then she would not have access to this information other than through the illegal conduct.  However, if you had a joint account with your husband and she shared his copy of the billing records with the girlfriend that would be a different matter in terms of showing damages.  The question arises how do you know she is doing this and what proof do you have?  Could she deny it?