You should keep contemporaneous records of the allegation that has been made. You should write down your recollection of the incident/s. Consider whether there is information to gather that might be helpful. For example, you might gather text messages, emails, Facebook postings, or other social media postings. If you have already deleted text messages, contact your phone carrier to find out if they can be recovered. If you think of possible witnesses, it might be helpful to write down their names so that you do not forget them later, when asked as part of the investigation.
You should write a reflection regarding the allegation.
Be aware that retaliation against a Complainant, or any behaviour that could be interpreted as such, will not only make the situation worse but result in additional complaints of misconduct and possible sanctions.
Do not contact the alleged Complainant or their friends through any means — in person, by phone, by mail, by social media, via electronic communication, or through someone else.