Ah another case of sith backstabbing you should of known that working with grathan wife that she will backstab you down the road. I let the wife live to see what it is like (cause people tell me that LS sith are still sith I hold the opinion that once you go light side you are not sith.) I knew she would betray me because thats what sith do and its the way of the dark side. Plus its foolish to trust a sith to keep their end of the deal. So I kill her and the son every single time I love being dark side.
So yes you where betrayed she used you to kill her husband so she can gain more power/ she used the promise of rewards to entice you to make a deal with her so in the end she manipulated you to get what she wants and wanted to get rid of you since you knew too much.