Yes, they most likely can be introduced in court: civil cases (like, say, divorce or matrimonial cases) do not have the protections against use of improperly obtained evidence (e.g. without consent or a warrant) that criminal cases have. While not all evidence or documents can be used in court, most can be, so long as it is relevant to the matter. While for a very definitive answer about your specific situation, you need to discuss with an attorney the facts regarding these texts or messages, such as who made these FB settings, how the messages, came to your husband, etc., as a general matter, these could be used in court.