We saw this kind of behavior, and worse, from daughter when son was still easy child. I think you need to take the bull by the horns on this one, hearthope. Your power in this situation is that you are providing a place for difficult child to live. YOU GET TO SET THE RULES.
So do it.
No prom for difficult child this year. This is easy child's time. You will not allow her embarrassed by difficult child's baloney. If difficult child crashes the prom, he is out.
Set a time for bathroom use. Tell difficult child, right out loud, that his attempts to sabotage easy child's efforts are pretty transparent and not very attractive ~ and that you will not stand for it.
Unless concrete steps toward GED are taken THIS WEEK, he is out.
Use this time, hearthope.
Mean what you say, and make it stick. You DO have power.
difficult child gets to choose his response.
If he wants to leave?
Let him.
Stay strong, hearthope. I know it doesn't feel like it, but right now is when you may have the power to change the course difficult child's life will take.
Dont let it slip by.
Know how I know this?
Because I had that same chance to save my son and I never even knew it.
Barbara