Ex husband tried taking our 17 year old off life support today....?

My 17 year old son is in ICU and on Life Support because he was shot twice. And So needless to say he has been really ummmm iffy on if he will be making it or not. But i had to leave the hospital for a bit because i had to pick my 10 year old son up from my parents house. And my sons girlfriend called me screaming and crying telling me my sons dad was trying to take our son off of life support. I have Custody and make all the legal medical decisions with our son so i do not get what my ex was trying to pull. I know he bough a 800k life insurance policy for our son. I just can't believe he tried this bs. Is there anything i can do with my ex? Advice?