My divorce judgement has language that describes the sharing of college expenses based upon each of our incomes of each year during college. The total costs are projected for what it would cost at the University of Oregon (even if they dont go there) including tuition, books, boarding and other incidental costs.
I hear you about the OM. My W at least told me that her OM tried to talk her into coming back to our marriage. Because of her OM's extreme age (68), he is more of a missing grandfather for my kids.