Terrified, seeing ds for first time since May

On the 19th (this coming Sunday) I will take my dd13 out to meet her dad in Kansas at the halfway meeting place, and my middle ds has agreed to ride along and meet with me to say hello and such. I'm planning on bringing his birthday gift and a Christmas present along, but other than that I don't know what to say to him. I have a huge knot in my stomach.

Part of me wants to confront my ex face to face as to why he purchased our ds yet another video game for his birthday instead of paying for the alternative school, so that he can go back to school, tell him he has 30 days to get him in school or I'm taking legal action, I still have residential custody and I never signed for ds to drop out. I have also offered to pay for this school.