Usually a person who sees life that way doesn't view the positive things about life and how much life really means. She will only see the negative things. I would recommend taking her out of school and have her transfered into another school. If that's not possible, just let her take a break from school for a while and let her be happy. Don't stress her out and be kind to her. The most important thing someone needs when in depression is love from family and others. If she keeps saying that she hates life, there are many special groups that help people get through bullying and depression disorders/problems. Make her see it as something positive, so she will give in. If she has to return to the school she is currently in, have your parents talk to the principal about it. Straighten things out. In some states (I dunno what state u liv in) bullying is illegal, believe it or not. So the bullies can get a penalty or a fine or whatever for bullying your sister, depending on how severe it is. Just speak to a lawyer about that if you consider the option. But first is first, let her take a break from school and be supper extra supportive. Then try to see what else you can do from the options that I mentioned early.