Hoping I've the good sense not to entwine myself in these situations often enough that the cooperation route becomes the best alternative, but rather as this is a one-off, ratting out the other guy is the best option; it offers no time or five years. let's also hope the other guy does intend to make trouble his vocation and plans for the long term.
Kindly
Were Christians ever to speak in non-ambiguous terms and listen with critical ears there would soon be no Christians for lack of agreement as to God plan.