Legal Question in Criminal Law in Missouri

Who charged him? If it was the stae of MIssouri, then the case is styled "State of Missouri vs. John Doe", not you or your son against John Doe. You and/or your son may be witnesses in the case, but it is not up to you how the case is handled by the prosecutor or the courts. You might be able to contact the prosecutor and request the opportunity to sign an affidavit of non-prosecution, but there is no guarantee that the prosecutor will drop the case. In many cases of domestic violence the alleged victim(s) want to drop the charges, but the prosecutors have seen these same alleged victims attacked again and again so they are not disposed to just drop everything and let the defendant have a second or multiple chances to do serious harm to the alleged victim(s). Your fiance, as you call him, needs to seek counseling or anger management therapy to have a chance to avoid this type of behavior in the future. Most people with experience in these matters would advise you to get that man out of your life immediately and permanently. In many cases the alleged victim(s) can benefit from counseling as well. Good luck.