I don't think your MD should be telling this to you, imo. Forgiveness, imo, is not something you can just choose to do or not do. I think that you should accept yourself for where you are right now, and keep working on moving forward, whatever that means to you. It might mean forgiveness for her, or you might move forward and try to get to a point where what she did no longer has an impact on you, or whatever you choose. I wish you well on this journey.