Borrowing that amount from your stepdad, even if he did agree to it for all 4 years and even if it were a good idea (which it isn’t) is a recipe for disaster for your mother’s marriage. Not only would he have the potential to control you, he’d be able to control her as well. For your mother’s sake, attend a school that you can afford. If that means a community college followed by a local 4-year school, then do that.