I was wondering if this is slander?

My son was falsely accused by a student at his college that he yelled an anti gay slur at him. My son was not in the area when the event occurred. He and his friends were followed and verbally attacked by the accuser and friends and they filmed the incident. The accuser posted on social media the accusation and my son's picture, college information and name. They did not contact the school and the school noted on twitter this was not the way to resolve the problem and gave instructions on how to contact the school. Now he is being harassed on social media, which he has since deleted all accounts. In addition my daughter's are being harassed by kids at their school. I contacted Twitter, the accuser (to take down the post) and the university. It has been shared over 100 times today and also shared on Instagram and other social media forums. He has since left the university, since he feels unsafe and won't be going back due to this incident. Could I sue for slander?