If you are supporting a survivor of an initiation, it is important that you take care of yourself and support  is available for you:

Students who are asked to participate in an initiation by a society or club that they have joined to gain status or entry to the group, should report this to the Students' Union Activities Officer.
Upon receipt of a report that a student or a group of students have participated in an initiation ceremony, the University will take appropriate action in accordance with the Student Disciplinary Procedure

There are two ways you can tell us what happened