I’d say the decision is up to him, ultimately, but it all depends on the consequences of his decision–will you divorce over it? How does he feel about this child?
As far as college expenses, those are not required to be paid by either parent unless he gave up that right in his custody agreement.
In my opinion it is going to split your marriage and put him in a terrible spot to choose between one decision and another. If the primary consideration is money, I would ask your pastor or a counselor for guidance, because acting on this will definitely have some very ugly and painful ramifications. Consider the child who will now have no one to call “dad.”