(a) If it appears that a defendant or the State is prejudiced by a joinder of related prosecutions or defendants in a single charge or by joinder of separate charges or defendants for trial the court may order separate trials, grant a severance of defendants, or provide any other relief as justice may require.
     (b) In the case of a prosecution of multiple defendants for criminal sexual assault, aggravated criminal sexual assault, predatory criminal sexual assault of a child, criminal sexual abuse, or aggravated criminal sexual abuse arising out of the same course of conduct, the court, in deciding a motion to sever the charges and try the defendants separately, must consider, subject to constitutional limitations, the impact upon the alleged victim of multiple trials requiring the victim’s testimony.