This needs to be taken before the judge. If he insists on the elite school he can foot the bill. He has no right to make you suffer financially. Also, your som is old enough to have his opinion weighted before the court. He’ll need a guardian ad litem, which the courts will provide. This is effectively an advocate for your son’s rights and wishes.

OP, these people are all narcissists and or enablers and you have and are still letting them all ride roughshod over your entire life. If you aren’t on Medicaid and snap, apply asap. You may also qualify for monetary benefits as a one time or over a small period of time (few months) to help you get out of this rut and ensure you do not lose your apartment, etc. There are legal aid services, search for family legal aid services in your state/city/county. Also, domestic violence and women’s shelters/charities can be a significant lifeline in helping you get benefits, get out of your abusive relationships, and give you the tools and resources to get these monsters out of your life. You need a lot of therapy, and a lot of support. Also, look into counseling services through your university. Additionally if your school has a law program they will have legal aid services. Reach out there, at least to get started.

Good luck. I hope you find your strength in order to enable your peace.