Michigan: Termination of support at 18, but may be ordered until 19 1/2 for completion of high school or beyond by agreement
No statute or case law holding parents to a duty to college support in the absence of an agreement.
If this wasn't in your custody/support agreement, the guidelines clearly state that there is no law to force the ex to pay thru college. Obtaining an increase in support was your obligation to follow thru with......I don't see how the court would feel that because you didn't proceed, he should be held liable for payment of support thru college and/or expenses.
KAT