The answer depends on what your divorce decree says. Ours says we have a “duty to inform about health, education, etc...”. Also if you are making educational decisions on behalf of your child without his input it is highly likely you have a duty to inform. Err on the side of caution and over communicate. You can put it in an email or a text and avoid the abuse. And you have evidence that you actually did your duty.
Also I’d start recording quietly. You can get an excellent USB device for around $20 that is small and will fit in your purse or pocket. Do NOT tell him and make sure it is legal in your state. In Texas I can record someone without their knowledge if I am a party to the conversation. We have 3 years worth of recordings we have turned over and have been able to demonstrate our claims much more easily.
Best of Luck!