Umm why wait 10 years to commit suicide

So she could kill the murderer. Her friend may have been the mastermind behind the crime but she used the stalker to kill Hara. So technically he was the actual murderer. Since he was put in prison and charged with the crimes (she probably let this happen for the sake of the police and Hara’s family to be able to close the case and have closure) she then had to wait for a chance to kill him which she was confident would come because his family had connections and was trying to get him released from prison.