If I cheated on my husband and we have sex can he still file divorce under adultry

The real question is whether he knows you cheated.  IF he knows you cheated and is still staying with you and you continue your relationship you may be able to avoid the adultery allegation.  However, in South Carolina there is no "unreconcible" differences.   The statute you are referring to as the "no fault" divorce in South Carolina is one year separation.  You can get divorced if you have been separate and apart for at least one year before the filing of the divorce. If you want a divorce quickly, this will not work for you, as the year does not start until you have separated from him (meaning apart from him and no more sleeping with him).