Consider this situation: the girl might have confessed to her family in the last moment that she loves some guy and will marry only him. Now as the deal with you has to be broken, that family is scrambling to save their face by blaming your side.
Meet them calmly and tell them to stand down. Tell them that you understand that they might have some good reason to do this and you stand with them in this decision. You are not their enemy, you are a considerate friend. Make them understand that they are doing overkill.