I'm so sorry, Daughter511. This is a very sad and stressful situation for you and your family. My father is also an alcoholic and has threatened/attempted suicide in the past.
First and foremost, take care of yourself right now! Your dad is in the hospital, where he is being taken care of. You and your family are suffering more right now than he is. The hospital won't let him out if they know he threatened to kill himself.
This is a very good site for you to find out more about addiction and alcoholism. Take some time to read the "stickies" in the Friends & Family forum, as well as in the Adult Children of Addicts/Alcoholics forum. There is some very useful information there.
We will be here for you.