GET HER HELP, LIKE YESTERDAY!!!!!!

You have an obligation as a parent to do something. If your husband did it than it is already in her head.Get her to a therapist ASAP!!!!! She is asking for help.You need to do it before it is to late.She will forgive you for reading her diary eventually.

I have to agree with lisak52. Your daughter needs help right away. She wrote it in her diary, and there is a family history of depression and suicide. Breaching trust by reading the diary is a point that you can both deal with once you see a counselor that specializes in depression and suicide, preferably one that works with teens. I would take this very seriously. There is probably a genetic and chemical factor that is making her behave this way. She may need both drug therapy and psychological therapy.

You have to get at the root of her problem. I suspect some of it has to do with her father's suicide. You definitely need to educate yourself more about teens and suicide as well. Here is one quote and a site:

"Most teens interviewed after making a suicide attempt say that they did it because they were trying to escape from a situation that seemed impossible to deal with or to get relief from really bad thoughts or feelings" (http://kidshealth.org/teen/your_mind/mental_health/suicide.html). This is a pretty good site that talks about depression, substance abuse, warning signs (though I think you already have that) and what you can do to help.

Mostly, though, I think you have to take her threats seriously, which I believe you are doing. The next step is to find someone knowledgeable that can help you. If you are in the U.S., you can go through her school or call a suicide prevention number for her (or get her to call), or take her to a hospital for evaluation. I'm not really sure what the procedures would be in another country.

Here is another good site (http://www.aacap.org/cs/root/facts_for_families/teen_suicide). Best of luck to you.