
Quoting
free9man
Was dad paying child support prior to this? When did the agreement stipulate support was to stop? Normal would be either 18 and/or out of high school although some can stipulate higher education as well. He is certainly able to come after you for support but it's up to the court to decide.
An 18-yr old is, by law in every state I know of, considered an adult able to make their own decisions in life. If an 18 year old wants to move out that's fine but the parent no longer legally responsible for them, absent some extenuating circumstance such as physical/mental developmental disability or support arrangement stipulating higher education.