Generally, if you ratify the contract after reaching the age of majority (18) then you cannot disaffirm a contract. Ratification is generally defined as acting toward the contract as if one intends to be bound by it. His continued attendance and benefit of the education is probably going to preclude him from disaffirming this contract.
We don’t have sufficient facts here to know if he reaffirmed the contract. But attending school would not be an act of reaffirmation of a
loan contract. Whether he actually attended school or not has nothing to do with accepting or rejecting the loan contract, i.e. accepting the obligation to pay as required under the contract. That loan contract is separate from the contract the student has with the school. The issue is whether he did anything that indicated his reaffirmation of his obligation to
pay the loan since that is what loan agreements are all about. Moreover, in Michigan, mere silence after reaching the age of majority is not enough to assume the former minor affirmed the contract. Under Michigan case law, in order to reaffirm, the OP needed to expressly state to the lender his intention to pay the loan:
If the deceased was a minor at the time of the execution of this note, the burden of proof was upon the plaintiff to show that he had ratified it after he attained his majority. It seems from the record that there was evidence tending to prove that deceased had not ratified the contract. The circuit judge was not authorized in law to presume a ratification because of the mere silence of the deceased for two years. There must have been an express promise after he became of age, or such acts as would have been equivalent to a new contract. Goodsell v. Myers, 3 Wend. 479; Wilcox v. Roath, 12 Conn. 550; Tucker v. Moreland, 10 Pet. 58; Ford v. Phillips, 1 Pick. 202; Fetrow v. Wiseman, 40 Ind. 148; Tyler, Inf. (2d Ed.) 84–92; Minock v. Shortridge, 21 Mich. 304; Prout v. Wiley, 28 Mich. 164.
Tyler v. Fleming, 68 Mich. 185, 187, 35 N.W. 902, 903 (1888)(underlining added). While that case is quite old, it is nevertheless still good law in that state. Thus, he might yet be able to disaffirm the contract if he has not yet affirmed it. Hence my suggestion that he see a Michigan contract attorney to review all the facts and advise on this issue. It may be that he did somewhere along the way reaffirm the contract, but there are no facts yet in this thread indicating that.