I have just got to let go of all that I can't control, and move forward. Let her find her own way. Let her discover what is important to her.
It is hard to let go and detach, I know I am going to struggle with this.
Just about all of us do/did. Read the link to the Livestrong.com article about Developing Detachment. Understand detaching is not about becoming emotionless. It's about going to the worst case scenario in your mind, taking it all in, and accepting and realizing you will be ok even in the worst case scenario. Work towards that realization. I don't think it's a light switch that can just be flipped on. That's why the artcile is called "Developing" Detachment.
What will help you right now is to put your focus on you and your sons. THAT's where your energy and effort should be.