If a student who was dependent (under 24 years old) gets married, they become independent.
If they get divorced, then they become dependent students again (unless they meet some some other criteria that makes them independent; having a child that the provide 51% support for, veteran, ward of the state after the age of 13, foster care after the age of 13, etc).
Your income and assets will be used to determine his eligibility for federal aid (it does not matter whether or not you file him on your taxes). On the day he files the fafsa, if he is divorced, he is a dependent student.