I have a contrary opinion. I think hatred is a human emotion and we have it for a reason. For one thing, it keeps us away from people who have hurt us. Are you still working with this woman? I think growlycat used a good word. She's a frenemy. Hatred is a terrible, painful emotion. In this case it sounds justified. However, carrying such pain may well contribute to your depression. Is there any way to decrease the intensity of the pain? It's there to protect you but sometimes it hurts, too. Maybe when you feel the hatred, validate it and say to yourself "Stay away, stay away."? You don't need this woman in your life, that's for sure. Hope one of you gets another job soon. That will happen eventually. Then you can "let it go" if you want.