Does the statement, "What about someone who disregards the marriage contract or legal documents, what would that make them?" constitute slandering the sister mentioned, and what are the repercussions of that, and what am I required to do given my inability to communicate with her?

The phrase "He who does... what is he?" is considered an innuendo of slander if, based on circumstantial evidence, it is understood to imply adultery, even if it is in a general form when the intended person is identified. It is not permissible to accuse a Muslim woman of adultery based merely on suspicion, for a customary marriage contract does not necessarily imply adultery. The questioner must repent for what they have uttered and seek forgiveness from the slandered person if possible; otherwise, they must seek Allah's forgiveness for her and increase their good deeds.