So sorry, Christina. Parenting is sure full of challenges.
You are right to expect him to finish his summer school before accommodating his desires/demands. You are a good mother!
I had some equally stressful situations with my kids. Not for any amount of money would I turn the clock back to when I had 4 teens!
Life gets better as they learn and grow. Just go into survival mode until then, I guess. Pray a lot.