It is wise for exes to reconcile to the point where they could be civil to each other. This is not a recommendation for dinners and joint shopping sprees. However, it makes sense for you, the new spouse-to-be, to be civil to the former partner. If there are children, divorced parents will have to communicate about their welfare, and step-parents also want to be involved in their lives. Everyone will benefit in an atmosphere that is void of resentment and hostility.