Using an ex's discount for two entire years without their knowledge is perhaps the best kind of revenge. Firstly, it's quiet. Secondly, no one is getting hurt. Finally, not only are you getting the emotional fulfillment and satisfaction of achieving payback, but you're also spending less money in the process. If that's not a two-for-one situation, I don't know what is. Here , we have a lady who frequently drives her step-kids to and from her husband's ex-wife's town to take them to school. The…