I’m sorry to hear that someone close to you has taken their life. It must be confusing trying to understand why someone would take such a fatal step. Many questions left unanswered, however, rest assured that it was not your fault. It was a fatal decision made by that individual. Blaming yourself is unfair to you and does not change the event that occurred. Instead, focus on the things you can control and are positive. Things that make you feel good and taking care of yourself.
If your thoughts become too overwhelming, find trusted support to confide in and talk out your thoughts and feelings. Journaling is also a great tool to get your thoughts and feelings out as opposed to holding them in.
Hope this helps,